A few years ago I did make my own tiles for Paris from OSM; it's pretty exciting to be able to design everything.
But it's a lot of work that has to be redone constantly to keep up with map changes... Not realistic for a small organization (or an individual!) unfortunately.
Oh, it's fairly realistic for an individual with `cron`, no worries. But the up-front setup is still nontrivial, and running a server costs at least power, if not system administration time.
In theory you could automate generating the tiles, but you can't really automate downloading the dataset; it's enormous (hundreds of Go IIRC) and most of the time has to be checked by hand.
Depends on the coverage. If you wish to serve the entire world, it is indeed massive (~100 GB indeed); but from my experience, the updates are 1.automated and, more importantly, 2.incremental. Perhaps the technology has advanced since you tried it... (How do you even check 100 GB of data by hand? That seems impossible.)
That said, I am using the dataset for generating a map, but I'm only using a country extract - which only goes up to some hundreds of MB, and updates on the order of tens of kilobytes. Far more manageable.
But it's a lot of work that has to be redone constantly to keep up with map changes... Not realistic for a small organization (or an individual!) unfortunately.