Volunteering has to do with helping people in need. When you do that, you realize the scope of how much fellow humans are in need. As social creatures, we humans can't but feel humbled and feel that there is still something meaningful worth striving for -- a sense of purpose. Given that we are all tech people here, it's safe to assume that daily needs and 'creature comforts' are so easily secured that we easily don't feel that sense of purpose as it pertains to ourselves. Volunteering connects with others who inherently have a sense of purpose, since they struggle, and the act of volunteering is an act of committing yourself to the purpose of helping fellow humans in need.
Traveling opens your mind to new people and new cultures. And those ideas can get you to re-think what you believe, and you can grow as a person. You can also learn things to make the world around you better. What is the culture around education in Finland, and why is their ed. system so good? If Americans increasing want public transit, what does European rail transit have to each us? How could Bus Rapid Transit pioneered in S. America be even better? How can some cultures in Africa and India be a peek into human history 4000 years ago? Does South India's plant-based cuisines have the tastiest answer to current diet and environment movements in the US?
We tech people & entrepreneurs are taught to build things that people want, so talk to users to find out what they want. We are also taught to leverage other experiences and ideas to inspire solutions to our problems at hand. It should be obvious, now, that both of those ideas are directly related to volunteering and traveling, respectively.