A century ago lever guns were still the dominant type of hunting rifle. That began changing after the end of WW I with large numbers of men who had been taught the bolt action in the service looking for something similar.
Today, lever guns still are a large share of hunting rifles, but not the dominant factor they once were. Also, today, lever guns are nearly exclusively hunting or pest guns or for nostalgia games. Competition rifles are now nearly entirely bolt action or semi auto.
SO, essentially the lever gun is a niche firearm. Its still a large niche but its not what it once was. Lever guns still rule in some places, but that is slowly changing as well. And I'm not talking about new sales, either. In some parts of the country, deer hunter are still using more than a few levers and others made pre WWII. Particularly in areas with lower income folks, where deer guns are once a year for a week or three use. Grampa's ole lever gun still brings home the venison so its still used. Especially by folks who are just getting by financially.
Look at the lever guns of today, (not counting .22s) the overwhelming majority are modern versions of pre 1900 Winchester/Browning or Marlin designs, and the Savage 99. More modern guns like the Win 88 failed the test of market longevity. Henry's are surviving, even doing well enough to keep introducing new models (which seem to resemble Winchesters more than original Henrys
) The BLR is still going, the Sako levers have gone away...
However the era of levers being everywhere in large numbers is about over, and they are no longer cheap because there were more levers than lever gun customers like there once were. Or so it seems to me...