In "olden days" there use to be a class of Tech that couldn't cut the 13 WPM test.
What they tended to do was put up a 6m station and settle for that.
These days, 6m is an exciting thing. It might not be year round, but for some people, with limited time, it might actually be attractive. You can work a lot of exciting DX every summer on 6 and also stateside if your station is more limited. Fred Fish could keep someone active for a very long time.
True, the "action" is mostly FT8 on 6m (with a vengeance), but since we're talking about the newly licensed, they won't know or care that some old coots think it is bad.
So, if we're losing a lot of techs (and, I haven't seen the evidence for that) it is probably because, like a lot of other hobbies, they tried it and never found anything to sustain their interest.
Ham numbers are reasonably stable. I have had trouble detecting one. About six months ago, someone posted up some numbers suggesting, for the first time, that there might be a decline. But, if it was more than statistical flux, it's going to take a long time to "do us in". Any other time these last 30 years, we've had between 600,000 and 700,000 US Hams.
Note: The nearby FCC License Count thread suggests nothing to panic about. It's currently around 770,000 total. "Technician" licenses are falling off, but that's because it's been "Tech Plus" for a lot of years now. There should be a decline in "Tech" licenses "as such". So, if that's what someone reacted to, it's an artifact of the data.