Ford and GM are behemoths which realistically don’t have much room to grow their market share/revenues very much. A win for them is not being eaten alive by competitors.
That being said, Tesla’s valuation (especially at its peak) was so high they basically are/were valued at at level where the “expectations” of the market is that they’d be the only vehicle manufacturer left on earth who will nearly capture the entire market. I think most will agree that is pretty far fetched and a lot has to do with hype/inflation/momentum/FOMO (it always goes up!).