I know everyone will hate me for this and say how it just can’t be, but sorry, you’re wrong.
The wisdom is that it’s nearly always impossible to be right about something contra an expert opinion. However, as already discussed, many experts aren’t really. This isn’t about them, though.
Most fields these day are too broad even for experts in those fields to know everything occurring, and to be well-versed in all the partitions and particularities of their area of study. Hence, it is quite easy if you’ve studied something intensively (if you have enough background to grasp the fundamentals) to know far more than the experts.
I know this is possible because I’ve done it myself often enough. For instance, I pay close attention to expert advice in economics and the stock market mostly so I can do the opposite.
When it was much harder (pre-internet), I also saw my grandfather spend months studying medical books, doctor’s reports, etc., so that he could learn how badly my great-grandmother’s physicians had fouled up her medications and diagnoses. And then I watched him fix it all. She went from essentially being clouded in a drug haze and bedridden to alert and active in the space of a week. It was amazing to see. And even though she was in her mid-80s, she lived many years after that. I don’t think she would’ve without my grandfather defying the doctors, the so-called experts.
Experts are just as human as anyone else. They only know so much, and often it’s surprisingly little. I always keep that in mind whenever I consult an expert for an opinion, especially if I already know a great deal about a subject.