Well i also notice this and i believe that people who buy BTC on its early stage and hold it for long time has now millions imagine, how high the btc go up and those who buy on year that the price of btc is still low and sell on year 2017 or 2021 they surely got a very big return from thier investments, so buying btc and holding it for 10 to 20 years is a good idea, i believe that it will become profitable and it will become a good investment because btc is always rising, sometimes it will hoes down but it will come back with much higher price.
If you had known that since that year and at that time you had time to buy more Bitcoin, you would also be very rich by now. Because on average, those who bought Bitcoin in the year you said were also able to sell it back at around $70K, which was before the halving. However, it would also be a shame if those of you who know about this also don't buy more Bitcoin so you just become spectators when other people take more profits via Bitcoin this year before the halving occurs.