However, during the past 3 years or so, I've constantly been overly alert
towards the possibility of hitting something in the sky.

[...] I feel I would be a better pilot if I could just let it go

Nope. If you "just let it go" you would be an accident waiting to
happen. While you are vigilant, you are doing exactly what you should
be doing.

I bought one of the passive collision devices, and every time something
shows up there, I try to figure out where it is, especially if I get a
reading around 1-2 nm away within +-500 feet. I know these things are not
excactly dead on most of the time, but they do tell you somethings out
there.

These devices are helpful, but one must be careful that one doesn't keep
their eyeballs inside the cockpit looking at the device instead of
outside. Like you, I don't always see the depicted traffic. Airplanes
look pretty small at two miles, and can easily get lost in ground
clutter or blue sky. They are probably not a collision hazard at that
distance if their track and yours diverge (though they could change
course). At two miles, unless they are moving straight towards you,
there is plenty of time to see and avoid.

I mean, what are the probabilities of hitting someone?

In the pattern, it's certainly a concern. Lots of people entering and
leaving, a few on odd courses, and some with no radio (or worse, bad
position reports). Eyeballs are put to maximum use. Over VORs is
another congestion point, and low down near airports is another hot
spot. In the mid thousands in cruise, it is far less likely to bump
into surprise aluminum, but it can happen.

Don't let the =fear= rule you, but do keep the =attention= outside
looking for traffic and keeping up with your position. You'll get to
relax and enjoy the view with more time in the air.

Jose




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