They're committing so early to reserve a spot somewhere until something potentially better or more lucrative comes along. They can get out of these commitments at the drop of a hat without recourse. What's the downside to committing early? It's insurance.Honestly I'm surprised to still see preps committing so early. I almost expect preps to start to wait until late in their senior season to commit potentially before the transfer portal opens or even during it.
That way you have a better idea of the situation/players on a team you're going to and you could potentially use the NIL money transfers are getting to negotiate and boost your own earnings.
Though I guess you could still just commit early and then reopen if you see an opportunity like a lot of guys are doing.