Yes, but you do the work of your main profession that you are an expert in, and are compensated appropriately. You don't do a side job bagging groceries or lifeguarding in the summers to be able to maintain living in a home you own.
Legitimate question, do you not see the difference?
I'll say that elementary school teacher who worked as a park ranger in the summer got a good deal as he still had a government job and instead of paying for a gym membership he got paid to walk around in a beautiful place all summer.
I'm sure most teachers don't have it so good but if one were trying to improve the current system you might try to create jobs that are complementary with teaching jobs.
Teaching is one of those areas like software development where the social contradictions are intense because it is a labor intensive practice with very little capital spending (think how the final assembly people on a car have a huge "gun" that hangs from the ceiling and looks like something out of Doom that screws all 5 nuts for a wheel with perfect torque in one shot.) Schools are also funded out of property taxes which are rather regressive and limit the ability of schools to be funded by people who have a huge amount of money and instead pits teachers against people who don't make $60,000 a year and who don't get a few months off in the summer.
Legitimate question, do you not see the difference?