I think if anything the best thing about having a paid system is that you have one less person to make happy. Unless your ads are just a dropin (e.g. google ads

I think if anything the best thing about having a paid system is that you have one less person to make happy. Unless your ads are just a dropin (e.g. google ads) you have to have a marketing and sales team, and presumably a bunch of coding work has to go into making a backend for advertisers to upload their ads and decide who sees what and so on.