There is a metric shit ton of pressure on these legacy automakers to compete with Tesla. Sure, you may think Tesla is a relatively small slice now, but the leaders at these companies are extremely scared of falling behind technologically to the point where they are uncompetitive. I'm quite sure a lot of people at GM were skeptical, but I bet a lot of them also did the subconscious calculation "What's worse for my career, losing out on a deal with an innovator like Nikola and falling even further behind, or going with Nikola, in which case if it fails we're not much worse off then we were originally?" Against this backdrop it's easy to see how a scammer can take advantage of this dynamic and even play legacy players off each other, e.g. "Well, you could choose not to invest in us, but then think how much further behind Tesla you'll be. And you know we're talking to Ford, too."
It will really only fail when the money dries up. As long as they can keep raising money, they can keep the fantasy alive long enough to lure in other investors.
It isn't a very profitable market.
And I assume you're referring to the automotive bailouts in 2008 when companies in many industries were falling apart and received bailouts or TARP funds? It was a rather unprecedented situation at the time, not really reflective of overall business viability.
Domestic OEMs have plenty of issues (poor innovation, arguably poor relative quality, unions, etc.) to criticize. Operating margins, which tend to be on par with foreign OEMs, aren't really one of them. And it really depends on what you're comparing it to to make a determination about how profitable the sector is. Pretty much nothing is as profitable as SaaS, but 4-5% is nothing to laugh at.
It's been modern economic theory that has encouraged this stripping of US industry...unfortunately it's a lauded theory.