Sell the top spots to them like parking meters or youtube superchats. Send so much BTC and then the time ticks down for their positions.
Spend it on a superbowl add for BTC

I think this is a joke. However the annoying part about this which hits home is that there are actually forums that do this sort of shit. Including several other crypto forums. Its ridiculous and wouldn't solve any problem at all. We already know that these projects are willing to spend money on spamming their threads up to the top because there are many services which offer bumping services. If the forum did this it would just be giving them permission to do it as long as they pay.