In a past life I ran a community using discourse where some people got competitive about reaching trust level 3, and frustrated when they did not reach it or retain it once they got it by continuing to meet the requirements. I tried a few things to assuage them but eventually just hid the trust levels so they were no longer distracted by them.
Personally, I would recommend creating more groups and badges to reward your users, and leave the trust levels as they are as long as things are working well for you otherwise. The trust level requirements are tuned already to protect and serve your community, so you don’t have to do too much manual intervention to deal with spammers etc.
Trust Level 3 provides near moderator level capabilities, so you don’t really want to have too many people automatically entering it without for sure having demonstrated that they are committed and trusted members of the community.
In case you have not already, see Understanding Discourse Trust Levels for more on how trust levels work.