A lot has been said on this topic and I agree with the overall sentiment of stagnation/downward trend.
Something that I haven’t seen a lot of on this thread or on e4 is the “collector cycle.” Most people enter a hobby for - on average - 12-24 months. Very few people leave a hobby the same year that they pick it up and most do not stay longer than two years. This is especially true in the TCG/CCG world.
Every boom and bust cycle is accompanied by an inflation in the collector base and a shedding of the excess when prices go back down. I believe that we are entering the “shedding” period where the prices will soften, the number of serious collectors will shrink, the amount of money spent on a given month/year will lessen, and some sellers - maybe even most - will begin to feel financial stress from their once-healthy hobby income.
1-2 years is a long time. Children grow up, teens graduate high school, college students change majors and eventually leave for the workforce, and adults change jobs, have families, and move around the country/world. Sticking with a hobby through major life events - including financially demanding life events (e.g., paying for college, a new baby, a home, etc.) - is extremely difficult. We may not feel this way because e4 is comprised of very serious collectors who would rather die than to leave their hobby, but this isn’t really the case among most people who enjoy shiny cardboard.