There are a lot of historical discussions about colonialism, guilt, reparations and consequences. But not much speaking about the positive benefits for the colonizer (morality aside, obviously).
So, from a purely economic perspective, was the occupation of Ireland profitable? Considering how many rebellions, revolutions and how much administrative and military effort had to be expended managing the colony, was it worth it for economic reasons?
Or were there other reasons that made it worth it?
More generally, was the European Colonial Horrific Dystopian Nightmare for Centuries (aka the age of exploration) worth it? From a purely economic stand point.
Morally it was obvious a real dick move.
Little attention is paid to Ireland when it comes to the success of British Colonialism. It's a little simplistic, but mostly true, in stating that the kinks of how to run a Colony was worked out in Ireland, a land that had never been centralised in any fashion.
So what were the primary economic attributes to the Island? Primarily it was good farmland, in the central plains we also seen livestock grazing, as well as fishing on the coast, but the real benefit was in the Ulster, Derry and Down county was arable land, where there was intensive colonisation (Commonly referred to as the Ulster plantations) carried out. Firstly mixed farming and then switching to grain for more monetary gain.
As well as this many canals were also built to facilitate trade all across the isle, and as farming became less important to the economic benefit of Great Britain, Ireland became able to stand toe-to-toe with the biggest colonies well into the seventeenth century as a hub for trade, as well as shipyards in Dublin, Cork and Derry, but also Belfast (which produced high quality textiles like linen) to feed Britain's famed navy.
In Irish families there was also a history of benefitting all children in inheritance; plots of land were divvied up between them*, so with many able to feed a larger family, they had them. The already substantial population of Ireland had grown to rival that of England by the 19th century.
As you noted though, Ireland has, for all it's qualities, been a difficult place to maintain, and from the Nine Years war all the way up to the Easter Rising, the British had a great mistrust of the Irish. When the potato famine came along, the massive tax base that had actually produced a surplus and the fact that it was the biggest trading partner of Britain at the time did little to encourage any alleviation. Food was ferried out of Ireland (which the Irish didn't legally own) while a blight stopped them from being able to grow potatoes (which they did). This caused a massive diaspora and crumbling of their population.
So even with the cities of Belfast and Dublin still being major players for trade and naval shipyards, Ireland was no longer worth the trouble it once was, and the Easter Rising and subsequent revolution illustrated that the taste for independence had not dampened. Coupled with more profitable colonial enterprises that were paying back with less effort than Ireland, partition eventually became more an ideological issue than an economic one.
Sources
Plumb, J.H., England in the 18th Century, 1973: "The Irish Empire"
Canny, Nicholas, Making Ireland British 1580–1650, Oxford University Press, Oxford 2003.
Braudel, Fernand, The Perspective of the World, vol III of Civilization and Capitalism (1979, in English 1985)
*If you ever visit Ireland I encourage you to see the small farms split with hedges all across the island, and compare it to the much larger farms in England, and even the gargantuan ones in the Midwestern US.
Are you assuming that the costs of colonialism were paid by the same economic entities to which the benefits of colonialism accrued? Lots of economic activity makes sense only if you distinguish who pays from who earns.