Let’s say there are 2 total Bitcoins in existence and a new one is minted every month. I hold one and you hold one. Now there are 10 other guys who want to buy some right now - not necessarily to hold but to get in on the new hot ICO. Let's assume you are not willing to sell your Bitcoin and I'm kind of undecided/may sell at the right price.
The 10 buyers may have to wait until next month and buy newly minted Bitcoin in an auction, and to meet their demand the last one will have to wait 10 months. Now some are quite patient and can wait, but in the meantime 20 other new guys just came to buy their ticket to get on a train.
30 buyers enter fierce competition for a couple of available Bitcoins, I may be willing to sell mine if the price is right for me, and here we go they start bidding it up. When I sell my one Bitcoin, it doesn't disappear, just changed hands. And pent up demand is still out there.
As long as the demand is strong and supply is limited, the price will stay high and may keep going higher.
FOMO is a real thing fear of missing out
The only problem is that Bitcoin isn't very scalable because it takes too long to verify the next coin, which is causing the transaction time and cost increase. I will be surprised if coins like Eth don't overtake Bitcoin in the next year! That being said, I think your correct in the fact that Bitcoin will continue to rise because it was the first coin, making it the most recognizable to new investors. Check out my page and if you think it's quality, please consider following me!