I know of no profession in which practitioners do not generally get better over time. Football players and Strippers don't automatically get better with time and despite learning new things their overall performance decreases with time. More generally any profession that deals with burnout either physical or mental has the same sort's of issues.
Look, my Mother has 2 PHD's in education and often does professional workshops for teachers. However, like most forms of professional development her workshops are both expensive and their value is hard to quantify. So it may pay better than her normal job but as she says it's of limited value.
Programming is a lot like teaching it takes a few years to get up to speed, but vary quickly years of experience stops being a useful metric.