I posted this the other day. I think most people agree the Germans make better interiors. But nobody can deny Tesla has a superior charging network, and for the vast majority of people their battery technology is superior (longer ranger, but more prone to overheating from aggressive driving).
I think Tesla is just riding the underdog wave extremely well - they're new, they're different, they're trendy, and they're eco-friendly. And honestly, if you're not a car person, their cars are fun and different (if you are an enthusiast you will likely have very mixed opinions of Tesla). Combine that with a CEO that can bend the laws of reality while he talks, promises for full self-driving which will absolutely never ever materialize, the fact that the competition is really quite slow to show up...and you get a ridiculous stock price.
I don't think Tesla is going away, but I think in 10 years they're going to be just another car company, especially if they shift their focus towards energy which is where the real money is for them.