SpaceX was already profitable by the time they were trying for propulsive re-use, they could afford to throw away as many first stages they needed to (after delivering payloads with them) to figure it out. The "one more failure and we go bankrupt" stage of SpaceX was well before that, when they were initially trying to launch a rocket.

Tesla's success is relevant to Elon Musk maintaining full control of SpaceX and funding mars mission research. It wasn't at all relevant at that point for whether or not SpaceX would continue to exist as a company, or succeed at re-use.