Counterpoint: https://simonrepp.com/faircamp/ already exists and is a self-hostable FOSS Bandcamp clone. Does it clone every feature? No. And it definitely has taken longer than a weekend to get to where it is. But it's a one-man passion project that clones enough to be a viable enough replacement for amateur musicians that I jumped to it immediately when Epic bought Bandcamp.
While a very nice project, Faircamp doesn't come close to offering what Bandcamp does. It's self-hosted, requiring the artists to have the technical knowledge to both customise the platform and run the infrastructure themselves, and it doesn't support any payment options other than a barebones liberapay implementation.[0]
It's also most importantly not a single trusted entity that people can trust with their payments like Bandcamp is.
