I doubt that it is very realistic to look at the past, pick a price and then just assume that a person would just buy lump sum and sit on their BTC until now.
There are more realistic scenarios.
Also, I doubt it is even productive to compare yourself to someone else, unless maybe you might be comparing one version of yourself to another version of yourself.
the very concept of looking at past Bitcoin price with a sense of regret of not buying earlier enough or a thought that if you had bought Bitcoin at the time it was at a certain price, you would have been in a certain percentage of profit is a mediocre way of reasoning because in the end, it's all imagination that doesn't translet to any change in the quantity of Bitcoin you now have in your portfolio.
If you've known Bitcoin at the time it's at $500 and even had the resource to buy it, chances are that if you're skeptical at the present that you wouldn't have brought even in that past. The past have gone and whatever decision you didn't make at the time should not feel ones mind in place of planning for what lies ahead of us in the future.
Instead of talking about past possibility that's already gone, it's best to concentrate on the present in anticipation of the future potentials of Bitcoin and how well we can be positioned ahead for it. We've seen a remarkable change in Bitcoin price from last week down to this point and that's relatively a small span of time if you're considering investing for the long term. In the future, the likelihood of Bitcoin going above $500k is eminent and because of that, it's only best to use this period to DCA upwards to that point instead of lamenting on what's already in the past.