There was never any "mining for massive profit. That is just a legend. Mining has never been more than slightly profitable.
I was thinking of those days where you can still mine with CPU. Let's not look back too far into the past... Even if someone mined bitcoins with a mid to highend GPU back in early 2013, and sold bitcoin at the peak. You can expect over 200% profit. Quite massive compared to the profit nowadays.
I agree that this has now evolved into a legend for new hopeful miners.
But the gain in your example is from holding bitcoins, and not from mining them. The way to measure mining profit is to subtract the cost of the equipment and power (in bitcoins) from the amount of bitcoins that are mined. Most miners pay more for the equipment (in bitcoins) than the equipment mines, and so they are losing money.