I feel 2017 gains was a once in a lifetime opportunity and we won't see anything like it again.
Many of the top 100 coins with a considerably small investment could have made you a millionaire today, and congrats to those who are.
$10000 in ETH at the time and you would never need to work again.
I just can't see these gains happening again, but anything can happen
Unfortunately for us I don't see any possibilities to see again those gains/increases of value. Many coins already have quite a high value, to increase so much we would need a huge amount of fresh money, and at the moment this is a very remote possibility.