If you buy 3 bitcoin and forget this for 10 years maybe you will become rich because they have possible the price will become $10,000 each bitcoin because the price everyear increase and I believe bitcoin will live long but it cannot live for more decades. Maybe 20 years is the maximum they live but I hope bitciin will live long . Many people for sure hold their bitcoin for their future. But remember no one can knows what happrn in the future maybe you can earn a lot of money but they have possible that your money gone.
It will take great patience to hold bitcoins for that long period of time as most of the people will start selling their coins when they see price going higher to make profits so there will be very few people who will manage to hold their coins with great level of discipline and there will be many who will get panic and may sell their coins at a wrong time.