The current method makes it difficult for newbies to have an influence in changing the order of topics, which is the reason that many ads use bots with beginner accounts.
You need to convince higher-ranked members to participate in your promotional campaign, either by using signature campaigns, paid evaluations, or other methods.
Trying to buy the ability to put your project bumping up will be useless, so try to make more effort to get higher interest from members and thus keep your topic up.