Finding a paper wallet, not stealing.
There is a big difference.
Finding something on the street or the beach and taking it is the same as stealing in many countries. Stealing does not have to be breaking and entering. If you walk behind someone who drops his phone or wallet and you pick it up and put it in your pocket, it's stealing. You didn't pull it out of the person's pocket but you still took something that doesn't belong to you.
It's not the same if I found a piece of land nobody is using, and if I kill someone and take away land from him.
An unused piece of land doesn't make it yours to take. Even if unused, it might belong to someone.
After reasonable amount of time I would give one part to charity or poor people, and I would just stake rest of the coins for future.
But that's the thing. What is a reasonable amount of time? 1 month, 1 year? 2 years? Has a reasonable amount of time passed since satoshi mined his bitcoin? Someone might say it has while others could say no. The truth is that it's a subjective decision. I make the decision what is a reasonable time before I spend my bitcoin, same as you. If one year is reasonable for me, maybe you consider 10 years to be reasonable.