you have a good point, it's much better to be working from passion than working for money. but when you're young, it's more about gaining experience. so the real question is "what should i do to gain the most relevant experience to prepare me for the future?"

summer jobs are a place where you get paid to learn. not only do you pick up technical skills, but you learn an assortment of soft skills (e.g. managing people, communicating, success metrics, company culture, etc). if working on your own projects will yield more relevant experience than at any summer job, then go out on your own.

in the end, summer vacation is long enough to learn a ridiculous amount, but short enough so that if you don't like it, you can grind through it.