Actually if the people behind are really enjoying the project or at least think that their project will disrupt the target niche or industry, then they don't think of incentives but rather how the will contribute. If they relax, then it's their downfall. Or maybe they don't really think that the project has a bright future if they don't improved on it.
Unfortunately, even those people behind the said project are enjoying the project, as soon as they received decent money during their ICO, we can't hide the fact that they are relaxed and not pressure at all.
One example is the CTX project that became a hype in bounty section
(on which bounty managers became scammers). After reaching their hardcap target, no such big development happen later on and now currently turned into dead coin. In here, looks like money received didn't push them to become more focus in the project but instead pay for a party or what.
Another reason is the 2018 dominance of the bear market which affects all coins/tokens in the crypto market. Luckily, some new projects back then survived but surely it will have a hard time to catch again their established all-time high price or never it will reach again.