Wait… that math does not possibly check out. In the worst case scenario (Steam), they pay 30% of the revenue from the game in platform fees. If they spend less than that for settlement, simple math tells us that there is at least 41% of the revenue basically unaccounted for.
There’s a bit of overhead in every company, like HR, IT and facilities, so maybe these don’t count for “development cost” (which makes no sense tbh, that’s not how project budgets work). Marketing can eat a ton of money, too, but the numbers still seem bafflingly high.
Here’s a whole bunch of modpack on Curseforge. There’s some more on FeedTheBeast, Modrinth and ATLauncher (I think). The scene is alive and well, although many of the old mods (like buildcraft and industrial craft) have long been replaced by newer mods.
Your best bet on jumping back in is a quest-based pack on a fairly recent version of the game. The last one I played was FTBSkies, which was pretty cool and included questlines for all major mods to guide you.