Correct, most people would regret not buying Bitcoin when it was cheap. Most people are invested in altcoins as they thought that altcoins are cheap and therefore they didn't buy bitcoin.
This is primarily the case with the retailers. The current price action shows that even when bitcoin is at 110,000$, altcoins aren't anywhere near the top; rather, most of the altcoins are close to their bottoms. Seems like the whales have played with the retail this time as they are holding BTC and there is no money flowing into altcoins.
They can use this calculator for estimation of how much money they would have if they bought an amount of bitcoins at a past day.
https://charts.bitbo.io/if-i-bought/I use it with $1000 for purchasing bitcoin in 1 January 2014, then I was able to
You would have bought 1.3259 BTC.
It's now worth 147,365.24 USD.
Profit: 146,365.24 USD
Return: 14,636.52%
Turning $1,000 to $147,365 from 2014 to 2025, it's amazing and only Bitcoin can do this.