The fact is, it would of been already incredibly hard for someone to be enthusiastic voting for Dems last presidential election; frankly even without even considering the utter and pointed moral failure with Gaza.
You want young people to vote, you can try to tut-tut them to vote for literally whoever, or you can, you know, listen to what they are saying, what they feel passionate about, and try even just a little bit to address it or, heck, put it on the platform. Its supposed to be a political party, something that unites people under some shared vision.
You want every single young person in the US to vote? Just say: free healthcare.