Comment by justapassenger

Owning entire stack has benefits for sure, especially if you're dominating market. But it also comes at a huge cost - you now need to pay for R&D for the whole stack yourself.

Tesla was dreaming of dominating market. But it looks like it peaked already and its sales are falling. Having to do R&D for entire stack without growth is a very very costly proposal. It often results in just not doing R&D, and falling behind.