Great write up! Only fools think that a $100 investment in bitcoin today will turn them into millionaires. This has to do with risk vs reward. A $100 investment in 2009 may have turned people into millionaires but at that time the chances of losing $100 were quite high. Now, with a lower risk than back in 2009 you're going to have to have greater skin in the game. $10,000 may see you with some good returns. You may still lose it but the chances are lower than back in 2009.
How high can it go? While your analysis based on market cap is mostly correct, unfortunately it's just a good guess. Bitcoin has the potential to replace currencies, MasterCard, Visa, Paypal, and more! Which of these will it do (if any)? Nobody knows. But if it replaced stuff, it's market cap would be way higher than the conservative 1% of X niche that you've estimated.
Personally, I'm optimistic for $10k. That's 10x now vs the 10,000x gain already seen since '09.
I have no clue whether it will go to 10k, 100k, or 1MM per bit coin. I'm on for the ride though and it's been pretty fun so far. I'm excited to see which problems bitcoin will solve and which industries it will disrupt.