Considering the supply vs global population = 0.003BTC per person to go around.
Then other factors like not all 21 million will be in circulation due to lost wallets/deceased hodlers who never informed anyone where their seed is, and also an increasing global population and future generations who all want in.
Do you think 0.1BTC will be like owning a mansion?
of course but when the bitcoin price reaches over $1 million. there are many predictions that predict bitcoin will be increasingly in demand in the future but it will be very difficult to get and that makes the price soar. the amount of bitcoin that can't be added and subtracted is really the perfect concept to make bitcoin high value.