"...another disease people actually get but also many more people claim to have without evidence."
Lyme disease can actually be detected. For IBS and long covid, you are making the "no true Scotsman" argument. Diagnosing those is basically filling a questionnaire asking in so many ways "do you feel like you have it?" The same is true for many mental illnesses, by the way. Not to discount people's experience of having these problems - they definitely are real - but since the "official" diagnose is very close to just people telling the doctor that they feel like they have it, self diagnosing is not as bad as you make it sound.
Lyme disease can actually be detected. For IBS and long covid, you are making the "no true Scotsman" argument. Diagnosing those is basically filling a questionnaire asking in so many ways "do you feel like you have it?" The same is true for many mental illnesses, by the way. Not to discount people's experience of having these problems - they definitely are real - but since the "official" diagnose is very close to just people telling the doctor that they feel like they have it, self diagnosing is not as bad as you make it sound.