Fluctuation in price should not stop anyone including youngsters in investing in bitcoin if they wish. With no responsibilities, I guess it is even the best time for them.
Every youngster should learn how to save, and bitcoin has actually provided an avenue and an incentive for everyone to learn how to save. Youngsters should be encouraged and not discouraged as it is their future. However, they could still diversify a bit if there are other options.
Volatility is ok when you start with nothing so long as the trend is reasonably up and you have a target to take profits at. I dont think its ok to use bitcoin for a pension like its for certain. Every young person has to save for pension and sooner their house deposit also I think. So a regular buy into volatile but prices moving up can work in their favour.
The old person near retirement who risks their savings and soon might not be earning more is much more restricted in their choices. If they went with bitcoin it would have to be far less then 10% maybe only 1% is justified really. Also the young person can say they have greater use for bitcoin as a global currency they might be able to use it when travelling in a more secure cheaper way then normal paper exchanges but in any a young person is more likely to use bitcoin across the internet globally. I dont think its right to buy bitcoin and not use it or to never sell it but to be involved certainly seems very reasonable and hopefully gains along the way as the world becomes more likely to use crypto currency every day.
So long as we have a move to greater usage by non technical people I'm fairly confident but dont only save in bitcoin, I dont agree with that as you need to pay house bills still!