Things I ponder:
I had a conversation with someone that was an "empath", and they described to me an incident where they stopped to help someone they were unsure was asleep or dead, but as they got closer they realized the person was still breathing.
After leaving their car in an area that obstructed traffic, and drawing the ire of someone who noticed this, they continued to provide aid to this unknown homeless person by means of restorative snack and electrolyte beverage. Towards the end of the encounter, the homeless person saw something that made them snap, and was then belligerent and verbally offensive towards the nice & helpful empath.
The question I was asked about this was, were they a fool for helping the person. To spot a person laying down (possibly asleep) from the road and to then get close to them, in a bad area of town, as a woman, alone...
There's a lot to unpack in this. But essentially they were upset that they did a nice thing for a stranger, and the stranger was mean to them (and luckily not physically violent).
And the question to put to me was, "was it wrong/foolish to help them".
Which has a simple answer, No. It's never dumb or foolish to help someone. (How one might choose the particular circumstances to put themselves in is a different story. )
But also, you if you automatically expect people to be nice to you Because you did something nice; then you're in for an unpleasant surprise. Certainly, we all hope people would feel inclined to be nice, but human beings are varied bundles of random feelings, experiences, temperaments, and not everyone is neurotypical.
Doing something nice is its own reward. Just know that some people will take it as a signal to walk all over you -or- as a sign that you might actually care about them.
It's okay to be nice to people. Being nice to people is great. Just also don't be shocked when it goes awry or doesn't go your way.
Also, if the reason you're nice to someone is for them to be nice back to you; you should take a hard look at what you're doing and the true reasons behind why.
Whether it's because you're filling a void in your life, or you crave the self pat on the back, dragging other people into it will not give you the fulfillment you seek.

Do nice things for people.
Tell no one.
Enjoy the sunset.
Repeat.