All that extra processing power for $20.00 more.
I know that due to the current shortages prices are all over the place, but you can still here in the US get a 4 with 4GB for $50 delivered give or take a few dollars.
Wow, I knew that each consecutive Pi added a bit more power, but never checked the numbers, and indeed the jump from 3 to 4 is insane!
I always had the issue though, that I bought a Raspberry Pi shortly before the new one came out, so I'm stuck with a 3B+ for almost as long as the model 4 exists.. Ugh. Now I don't want to make the same mistake again and buy a model 4 now if maybe next month a 5 comes out lol.
Anyway, my Bitcoin stuff just runs on on older Intel platform, which is probably still faster than a Pi model 4 (though of course much higher power consumption). Easier to work with in general, e.g. apt updates take forever on Pis (at least anything up to including 3B+).