[Will Dawson]

Sure money can bring in more youtubers, however that doesn't mean participation would increase across the board. Take The Simpit series for example, I know for a fact that at least a third of the people that participate in that series don't participate in anything else and are only here because they're Simpit fans and if Simpit stopped sponsoring a series they would forget about SRS. As it is now where they are sponsoring series for mutual advertisement it's fine because a few of them will stick around and participate in other series. If you start giving money out to youtubers to sponsor a series then you would have to pay them all. The cost wouldn't be worth the small amount of new regulars that would be retained.
Then you have to consider that this may push away the regulars that are already here.

I hope someday that SRS is big enough and populated enough that a fee could be implemented with little risk and high reward to the admin... However I don't think that time is now. The best option I see for right now is ads and donations.
This is just my opinion of course and should be regarded as such, I am by no means a business guru.