Is this realistic?
Yes, it's realistic. There were even predictions that it won't take to a decade until we reach a million so your is even longer but realistic too.
Is this a prime time to buy?
You're on it if you feel that you should buy it with that goal. So, looking at the numbers that if someone has that longer stay of time and is looking forward to $800k and more in the future, prime time to buy? Definitely.