For myself - I've got projects I've helped as above. I'm not a maintenance/sustaining kind of guy, but many companies gamble on a "make it work now" scenario and then need help after the fact to bring it back to reality for long term support.
It's not sexy, I don't do it often, but if someone has an interesting challenge to get from X to sustaining, I'm happy to hear and maybe work something out biz wise.
HN has a VC/startup focus. Maintainable code means a lot less to a quickly growing (and possibly pivoting) startup because fast growth almost always outruns the maintenance burden.
On the other hand poorly written and maintained software can drown a normal business. These companies typically have 20-30% margins and so even doubling the cost of maintenance can remove any profit.