Beyond the fact that snipers will just attack the top zapper spot, it'd be much better if there wasn't a DM invoice and instead replied with a comment on the post that the OP would just zap. This would give public confirmation that it was paid so users don't use tagging @buzzbot as a fake engagement trick in itself. I'd also let users customize their preferred % breakdown for what they want to see boosted and offer other functions instead of just Top Zapper which will just be gamed like I opened with.