There are a lot of bots out there which follow ad links for "research". I get them a lot when mailing nowadays. The vast majority of them are coming from AWS IP ranges, but there are also a lot coming from MS and Google - basically the popular cloud providers. Unfortunately with PPC you have no control over who clicks and what is counted as a click, so I would say the value of PPC is even lower now than ever before. There are a lot of bullshitters who claim to be doing well with PPC and maybe some of them do, but they're never telling you the full story.