Any time somebody already planned to replace their car and chooses electric over ICE is a win for the planet. It's also a health improvement for humans living in urban environments.
Tesla might not be selling that many cars, but they are the major reason why established brands like Volkswagen feel pressure to "catch up" and massively invest in new EV lineups. Once those companies have caught up in terms of technology and lineup they will massively outsell anything Tesla is capable of, helping reduce our impact on the climate and our health.
Of course public transport would be even better, but don't let the perfect be the enemy of the good