The meme is talking about a common probability error that surveys have shown even doctors are prone to making.
Why you’re probably ok:
The rarity of the disease far exceeds the error rate of the positive test. Meaning, the disease occurs in 1 out of a million people, so if you are tested at random and show positive, you only have a 1 out of 30,000 chance (the 3% false-positive rate) of being the the 1 person who truly has the disease.
This is one of the main reasons doctors don’t ‘just give you a battery of tests’. Not only is that expensive, but if you are running dozens of tests, the chance one of them gives a false positive is pretty high. So now you not only wasted a pile of money, but you also think you have some rare disease you don’t actually have. So you waste even more time and money treating that disease you don’t have.
Doctors run tests for things they think you might actually have, which diminishes the false positive chance.