Yes he is right, but it is an outlier (less than top 5 percent). How to convince them? You need to have a good skillsets. But I believe normally this people without programming background can pick up quickly because they have a high IQ (they are normally good at math during uni time).
For the person with 4 years exp, it is possible to command 10k but you should be good at management as well (being a leader) not only programming unless you are working at FANG companies.
It is like insurance, you dont need a degree, but if you are at the top of 5 percent, you can easily draw 200k regardless of your exp.