Listen, this sort of argumentation creates mistrust. If this is how seemingly rational people argue (and dear god i hope it's not) then no wonder there is a lot of mistrust in society around these matters. Or maybe you were sarcastic, and in that case, you got me!
To say that the evidence would have been here now is simply not true because we can't possibly know WHEN symptoms will present.
What would be more appropriate would be to say that in the time frame from when people started getting vaccinated until now it doesn't seem like the vaccines are causing to many serious side effects. That is fair to say. What about in 5 years? We DON'T know. This is a fact.
Actually, we can. Vaccination isn’t long-term exposure but a brief immune trigger — this is very different from medication being taken over a long term because the vaccine is only in your body for such a short period of time. In the multi-century history of vaccination, side effects are almost always immediate and the longest delays are measured in weeks, not years. There’s no mechanism for a longer reaction time because your immune system doesn’t work that way.
What could be the risks of taking booster shots every 6 months?