The phenomenon meant by the OP undoubtedly exists, but the phrase "purely to make money" does not describe it properly. I suggest "Successful songs in whose message the writer did not believe". Evidence can be either the song itself, in which case it is a bad song, or knowledge about the writer's convictions or lifestyle.

For example, the hippie movement was shamelessly exploited by writers whose lifestyle was definitely bourgeois. Nevertheless, they may have had fun and artistic satisfaction from disguising as hippies.

We must face it: entertainment business, including serious art and literature, will always look for trends in society to exploit. We may call that cynicism, but what really counts is the results.