I think if the party establishment threw its support behind him he would win a rigged primary. There's a reason everyone coordinated their drop-outs and endorsed Biden in 2020 before Super Tuesday. If they'd wanted it to be Pete, it would've been Pete. But because the DNC is a gerontocracy it wasn't "his turn" and that's how we got stuck with Biden in 2024. The establishment loves that Pete has been vetted by the consultant class and is comfortable among donors and coastal elites. They love that he can say he's done "active duty" but also that he has an ivy league education. He was placed on Biden's cabinet precisely because the DNC wanted to fast-track him for future presidential races, when it will be "his turn."
Bottom line? Pete can win a primary even without the support of leftist Democrats, so long as he's anointed by the party bigwigs behind the scenes who will shamelessly put their thumbs on scales.
Pete's problem is that all of the party's power evaporates in a general election, and the leftists who could help you win a general election (many of whom aren't Democrats) are gonna stay home because based on their lived experiences (nothing good from Bush, nothing good from Obama, nothing good from Trump I, nothing good from Biden, nothing good from Trump II) they perceive no difference between the party's anointed nominee (whose platform will be "Sissy Sause" Fascism with a side of Civility™ and Competency™) and JD Vance ("Original Sause" Fascism).
The party actually believes that a $20M focus group will give them the answer to reclaiming young men and Latinos. I don't know who sold them on that pipe dream, but it really captures how thin their playbook is. It's like being stuck in a 20-foot hole you dug and deciding the cause of the problem is that you used the wrong type of shovel--the kind of thinking only a self-interested shovel company would endorse.
The things about Pete that you, a college graduate with assets and a career, admire so much about him (he's articulate, thoughtful, accomplished, demonstrably competent) are the same things that are disqualifying for enough people in enough swing states that the only way to overcome that disadvantage is by making a convincing case that he's not just another neoliberal democrat willing to say whatever he thinks the people want to hear. I don't think Pete can make that case convincingly to leftists, even if he goes on their podcasts.