If I power down then I won't have the resources to help various individuals and communities. No point in being a witness if no residual benefit aside from the obvious block production and price feed maintenance comes from it; the goal is to support the blockchain in other ways and promote it. Otherwise there'll be no blockchain to witness for.

What I do instead is fund the witness through my unrelated earnings on the platform. I fund our dev bank with that as well. Even if I powered it all down, the SP wouldn't be nearly enough to fund the hours for a single project.

Not all witnesses have projects. Not going to call anyone out but I can think of a few that do jack.