I can't speak for the commenter above, but as someone who runs a paid service built on open geodata I can tell you our best customers are those who first try to self host and then realize what a pain that is. The challenge is not just keeping the software up to date, but that you also need to keep the data fresh. How fresh of course depends on your exact use case, of course, but for perspective OpenStreetMap has 3-4 million edits per day. It's totally doable - and is technically very interesting, but in much the same way that fixing your own car or baking your own bread is doable and fun. It's more cost-effective to hand it off to a reliable expert.
Building/installing is (relatively) easy. Maintaining is hard.
Even without a requirement to stay particularly up to date, the size of the datasets makes working with OpenStreetMap reasonably complicated.
I needed tiles in non-web-standard projections: equirectangular and polar (EPSG:4326, 3575 and 3031). ESRI used to provide equirectangular tiles[0], but have deprecated the service. Polarmap have an Arctic map, but only at standard resolution [1]. I couldn't find an Antarctic map.
With a fair amount of fiddling, and building on the work OpenMapTiles.org have done, it was possible to generate the tiles, but I now realise why few people have attempted this: it requires a lot of processing power, technical ability to get everything working properly, and cartography to have a map that looks good (not just the final styling, but the choice of what data is present in each layer of vector tiles).
I met the minimum of what we needed [2], but I need to find more time to do the rest -- like contours.
