Although growing nicely, BEV sales still remain a small percentage of the overall car market. There is plenty of time for companies new and old to come in and capture significant pieces of that barely touched pie. Tesla may currently be the dominant player in BEVs (just as Netscape had once been the dominant player in browsers, Nokia had once been the dominant player in cell phones, etc.) but things can change pretty quickly and not necessarily favorably for first mover companies like Tesla.
Their opportunity is slowly going away as Tesla continues to scale. I think you're going to be very surprised in 10 years when Tesla captures 40+% of the market with 100% of the industry's profit.