Society is like a framework you build upon, without the scaffolding there to hold you up and none of what you accomplished would be possible. None. In turn, it is our responsibility to manage the upkeep of society.
I grew up on open source software. I started using Debian when I was still in grade school. Without it, many of us wouldn't be doing what we are now.
In advocating that volunteering charity as a solution to society's ills, you need to consider the cases that charity simply can't or won't make a meaningful impact on. You also have to factor in the marketability, trends, and prejudice that will invariably select equally worthy social causes over another. We've seen how without a proper safety net, the public at large will let the sick and poor rot, then charities and business went on just as usual and profits and donations were better than ever. Yet we still denied the mentally ill the healthcare they needed to take care of themselves. We vilified and locked up the poor and minorities.
Business as usual hasn't addressed what didn't directly benefit business (why would it?). Think of the cases that open source software tackled as a community that lead a richer software environment. We were no longer at the whim of the walled-garden software giants. We saw how without proper disruption in business as usual we were screwed.
Remember, we are lucky and privileged to be in a position where we can almost assuredly find (self)employment on our own terms and be guaranteed high salaries. That can change, and you can bet that employers will jump at any opportunity to bring costs down so in the long run our position will be whittled to maximize profit. The next generation of programmers will experience lower entry level pay + benefits and that trend will follow them throughout their life. They will never see the level of privilege we experience now. This is the trend almost every middle class profession has seen in the last 30 years.
We can effectively be exiled from the walled-garden, and every paycheck you employer hands you is another reason to find a way to replace you. The vast majority people are experiencing this.
We created an environment where there is no alternative to the pittance the wealth giants feel like granting us. It gave us a shitty software environment and locked down hardware, and it never addressed the scope of the problems government, welfare and public works solves.
>And why do I owe it to society as a whole and not some particular individuals?
When you pay for your meal at a restaurant, are you only paying the specific people who prepared and handled your food? Again, specific individuals didn't accomplish anything in a vacuum. You are a by product of society as a whole just as your meal was the product of the restaurant as a whole.