at what point did science become a personal-profit motive and completely void of the basic curiosity and survival focus that earlier scientists and protoscientists had?

I disagree with this premise. Scientists today still have a basic curiosity about the world.

You're really talking about money, and how it drives scientific thought. The only people who could indulge in science free of financial constraints were the original independently wealthy citizen scientists of the renaissance, or those who had patronage from some ruler.

The modern equivalent is academics in a university doing 'pure' research without having their fields dictated to them. That still happens a bit, but the modern publishing model is a bit broken insofar as discoveries and 'statistical significance' go, and the utter contempt that reproduce-ability has.

Science has never been "pure" in the sense that practical applications, including those of commerce and military, were always part of its work. We often ignore those practical concerns today when we talk about famous scientists, but if you dig into their histories, they are there. Galileo made his money in part by teaching young nobles how to do ballistic calculations for warfare; many of Newton's interests map directly onto the concerns of the late-17th century British state. Archimedes built military machines. To point these things out does not besmirch them or the quality of their knowledge — it just means that their work was done in a historical context and that it reflects that fact. This should not be a radical statement, but some see it as impinging on the notion of objectivity and so it does attract criticism.

All that being said — which is to say, to dispense with the myth of a lost purity — there have also long been parts of science that are concerned with what we call in the post-WWII period "basic" research, which do not have any specific application in mind and are just for knowledge's sake. These still continue today and arguably are better funded and supported than they have ever been (because of the existence of funding bodies that exist specifically for these purposes, which are basically a 20th century creation).

(The categories of "basic" and "applied" can also obscure the fact that there is much in between them in terms of individual scientists' motivations, whether they are religious, political, philosophical, and so on.)

In terms of broad categorizations: industrial science really picks up in the 19th century, during the late stage of the industrial revolution, when it becomes apparent that scientific practice can really produce wonders. That is perhaps what you're thinking of when you talk about science as a "profit-driven" endeavor (which isn't quite right as a characterization of all science — it is just a sector).

Necessary reading: Steven Shapin, Never Pure (Johns Hopkins University Press, 2010). If you are curious about my Galileo example, Biagioli's Galileo, Courtier (1993) is all about the nuts and bolts of how Galileo paid the rent; on Newton, Boris Hessen's "The Social and Economic Roots of Newton's Principia" (1931) is a classic in the genre.

I think there are a few factors at play in regards to how scientific research has been driven.

First, as science has progressed, the cost and difficulty in achieving advances has increased dramatically, while the magnitude of the advances has greatly diminished. In the early days of scientific research, major advancements could be made with only observations made with the naked eye, a hypothesis to test, and the application of the scientific method. Other massive discoveries required only simple technologies like thermometers, lenses, scales, etc.. Some of this would have been considered expensive and high tech at the time, but wasn't beyond the means of a successful burgher or a well-funded scholar, let alone a member of the landed gentry. In addition, the breadth and depth of knowledge needed to master these instruments, make them yourself, and still have expertise in other disciplines was not beyond the faculty of a single individual. As the low hanging fruit got picked, scientific discovery began to require observation of the smaller, the farther, the deeper, the fainter, the fleeting, the subtler, and the invisible. The instruments needed to take these observations became more precise, more complex, more technologically advanced and the amount of expertise needed to design, build, and operate these instruments expanded to the point that it took many people. Extreme modern examples would be space telescopes and particle accelerators, but even something like a digital scale or a laser takes armies of engineers and others in the supply chain. Cutting-edge basic science being done in a one-man lab is unheard of in the present, but was absolutely viable in the early scientific era.

Further, as the scientific knowledge yielded by the cumulative scientific research grew overtime, so did the need for scientists to specialize in order to push the frontier back further.

Another factor is that, during this time that such advances could be made by an individual or just in collaboration with a few, there were many individuals in Europe who had plenty of free time and resources that they could devote to following their curiosity where it may go. Landed gentry could occupy their time with scientific pursuits or merely bankroll a scientists (or natural philosopher or whatever they may have styled themselves as) out of interest or vanity. We still have some people who would best be described as the "idle rich", but the diminishing marginal returns and increasing cost of new advances has largely put them out of the scientific progress game. Now there are few entities outside of governments that have the means to find advanced research without realizing returns on the investment. Yet some scientific advances can bring back fantastic returns, or a least a good return, and so where there is money to be made, science is funded by those who stand to profit from it.