Financial options have existed for a long long time. Though moneylending and interest were banned/shunned in some religions, ways were found around these rules, either through the use of religious minorities (Jews in much or Europe) or loopholes (cash waqfs in the Muslim world). Charters and companies preceded the stock market, and involvement in trade preceded that- you could fund an artisan and make them pay rent, you could provide capital for a caravan so they can buy more camels/supplies, etc. If you had the connections (or conquest) you could even bring experts from far afield to start new industries under your watch.

Though it's important today too, prestige also played a bigger role in the past. The most obvious were honorary/obsolete titles- particularly in large imperial regimes like the Byzantines but also in smaller kingdoms like England, titles like "keeper of the swans" or "chief gardener" etc could become titles with no real responsibility, but hefty salaries, bestowed politically.

In more imperial systems like the Ottomans, governorship and taxing rights would be distributed regularly (instead of hereditarily passed on as was the usual case in more feudal systems), meaning vying for these would be a way to generate cash flow. Especially in more monetised economies (Ancient Rome, Early Modern Ottoman) the rich could sidle their way into the elite through gifts and investments, which would then unlock reserved opportunities like tax farming, governor positions, and more (though such mobility was far less compared to the modern day, and often shunned by hereditary elites, who routinely attempted to legislate against such upstarts).

TL;DR: finance, trade, craft, prestige.