Something I notice when people talk about the dot com bubble is they focus on the extremes -- Trash companies like pets.com went bankrupt and Amazon, Microsoft, Apple survived to become the most valuable companies in the world.
It leaves out that there were a lot of good companies like Oracle, ASML, ARM, and Intuit that took 10-15 years to surpass those 2000 highs. Even worse there are companies like Intel and Cisco that never got back there. Again, all strong and well performing companies.
By ignoring those middle companies, some (more novice) investors think that buying a good company and just holding for a long enough time period will guarantee a higher return even if we have a market crash. Price matters though.
I say all that to say, even if you believe in a company, you should always look to average down your cost if you have the ability to do so. If you started a position in a company in Dec-Feb at an ATH and it's down bad now but you've researched and still believe in it, then buy a little more.