I looked at pph many times, but there are people who reply from all over the world so you can find yourself competing with anyone competent in English from a poorly paid developing country. So don't expect to make your fortune.
What I did find out from pph was the amazing and diverse range of very specific topics that exist.
If you want to make money then forget your own ego and soap-box topics, and look at where you can develop a niche. If you want to write about gardening, don't go for the popular generic topics but instead research obscure varieties of Japanese leeks, if you want to write about health and diet then become the expert on the natural sources of a rare and essential vitamin.
And then rather than relying on random adverts, go out and find people who need your writing skills....
I did some work for a chemical engineering company - one day facilitating a workshop. I knew nothing about the topic, but if you're a skilled listener and writer then you could very quickly spot why they were having difficulty in communicating with their wider customer base. I drafted a couple of articles for their technical newsletter - now a regular (if occasional) source of income.
I was at a friend's house one night when her husband (a director of a charity) was moaning that they couldn't recruit volunteers. No wonder! The information about the charity was written by professional staff and was full of technical jargon. I re-wrote it for him and then their comms department gave me contract re-writing all their volunteering training programme.
Just a couple of examples of writing for a living. But not the kind of dream-making stuff that the other poster may have been imagining....
.... however I do have a dream niche, and I do make money from that, but it took a long time to build up and (for me) that couldn't have happened if I'd not been doing other work too.
Good luck. It's a fascinating way to make your living.