Believing UFOs are actively visiting earth requires the following assumptions.
1. There has at some point been life off earth
2. That there is currently life off earth.
3. That there is currently life off earth but relatively nearby (in this galaxy).
4. That the nearby life off earth has evolved intelligence and still exists.
5. That this intelligent life has developed a scientific civilization (see whales / elephants).
6. That the life off earth and nearby with a scientific civilization has developed spaceflight.
7. That the current life off earth nearby with intelligence and a scientific civilization and spaceflight has noticed us.
8. That the current life off earth nearby with intelligence and a scientific civilization and spaceflight and that has noticed us has a means to get here in a timely manner.
9. That the current life off earth nearby with intelligence and a scientific civilization and spaceflight and that has noticed us and a means to get here in a timely manner has visited us yet refuses to make contact in a public way, preferring to kidnap rednecks.
10. That the current life off earth nearby with intelligence and a scientific civilization and spaceflight and that has noticed us and a means to get here in a timely manner and visits us yet refuses to make contact in a public way, preferring to kidnap rednecks has been able to be covered up by the government as easily explainable phenomenon.
I will accept 1-3 as extremely likely, 4 as possible and anything else as highly unlikely at best. Especially when the alternate explanation is "crackpots are seeing patterns where there are none"
Theoretically possible, statistically, improbable almost to the point of certain impossibility.