>Plus the PHP market, and especially the Wordpress market, doesn't tend to do great in the compensation department
WordPress work certainly doesn't pay a lot, but for PHP in general there's a large cavern in the middle. You can get very, very high salaries/contract rates as someone experienced with PHP if you are extremely experienced with PHP - specifically because so few people are willing to stick with it to that point. There are just a lot of legacy systems in very large companies that run on it.
So if you already have the experience, it can be worth it. If you don't, then trying to get mid level or even "low senior" PHP jobs probably isn't worth it compared to another skillset.
Yeah, I know there exist high-paying PHP jobs, it's just that finding a PHP job that pays as much as Swift or C# or Java or Javascript or [insert almost anything else here] is usually relatively challenging.
I don't mean that there are zero people making good money in PHP, just that it requires flying a rather tricker and less-certain course to get there, than with other options.
I really might put PHP top-of-page—at least, in some contexts—if marketing myself as a high-priced contractor, for the reasons you mention... but, in hunting for ordinary jobs, I no longer even bother looking at PHP listings. Too much chaff, not enough wheat, and it's been like that for a decade or more. Just way easier to find an employer with compatible pay expectations, with other languages, if we're talking run-of-the-mill jobs. Shorter searches, more-consistent outcomes.
WordPress work certainly doesn't pay a lot, but for PHP in general there's a large cavern in the middle. You can get very, very high salaries/contract rates as someone experienced with PHP if you are extremely experienced with PHP - specifically because so few people are willing to stick with it to that point. There are just a lot of legacy systems in very large companies that run on it.
So if you already have the experience, it can be worth it. If you don't, then trying to get mid level or even "low senior" PHP jobs probably isn't worth it compared to another skillset.