Volunteering is nice but I think rarely takes up enough time to be a significant part of one's life. I'm not going to form deep connections with people or feel a deep sense of accomplishment volunteering somewhere for an hour or two a week.
Even if I quit my job, lived off savings and did volunteer work full-time, I'm likely not going to run into many other people like that. I could start taking a more active role and organizing, maybe with other full-time volunteers.
The work I'm doing while volunteering is also generally likely going to be less interesting to me than the software engineering work at a tech company. Maybe I'd be doing some kind of software engineering work full-time at a non-profit.
But at that point I've just traded in my job at a tech company with one at a non-profit. Ignoring whether this is better for the world overall (I'm skeptical it is, but whatever), how is it better for me?
edit: Not to imply that for some people, full-time work at a volunteer or non-profit organization can't be fulfilling, but I'm very skeptical that this is the case for most, or even many people.