The third option is living within your means while providing a free service for the public good.
Don't disagree with you, assuming you have some form of "means" that provides the basic necessities. All of us have a responsibility to give back our time and talents to others, in whatever manner we can. Over the years, I've spent literally thousands of unpaid hours as a VF and First Responder, and continue to serve in the department as an adviser and board member, but I was fortunate like you I've always had sufficient income to provide for the necessities. I suspect that was the basis of the earlier comment.
Understand and appreciate your response. I agree that to do pro bono work, one needs at least some financial security to pay the bills. However, pro bono work is not strictly made up by charging others more.
I'm not trying to get snarky, so please don't misunderstand. Pro bono work is essentially voluntarily taking on work for free. We all know this.
What I'm saying is that when it was stated in this thread, it was alongside a definition that indicated that the "free work" was then explicitly made up by charging others extra. If you charge others more as a direct result of "free work", that's not pro bono, at least not to me.
For example, if I were to volunteer for my local community, and I had to take a day off work, I am personally responsible for that time. I make the time up by working four 10 hour days (to get to 40 hours full-time), or I just don't get paid for that day and choose to take the loss. I don't turnaround and charge my clients extra for that time off for increased overhead. I don't raise my multiplier to get more money. I would be volunteering for the public good, so I freely give up that time, which I see as a benefit to the community. If I can't do it financially, then I may choose to volunteer on weekends when I'm not "on-the-clock".
Rather than donating money explicitly, one would be donating time and effort. Yes, that is "equal" to money, but some people enjoy helping out physically rather than financially. An attorney can do things for free that they may normally charge thousands of dollars for (because they have the expertise and the license). Given the right circumstances and the right clients, an attorney may be very willing to help out for free.