I feel bad for how much my parents are spending on my education

I don't expect any responses–I just need this space to get this off my chest, so apologies for the long post ahead. I am going to be a senior next year and I decided late last semester to do a thesis. It's not required for me to graduate, but I decided to do it for personal development reasons, potential graduate school, and just as a passion project. I won't go into too many details but it's about a country that means a whole lot to me and my family, and I really want to learn more about it. My thesis advisor suggested that I travel there this summer. So, my parents and I booked a flight and we plan to stay there for all of July. In terms of research, that's not very long, but for me, it's the longest I have ever been outside of the country. Since I decided so late to do this project, I missed all of the international research grants, scholarships, and funding opportunities. I've been beating myself up for it, wishing that I could have been inspired to do this project just a little earlier. But it's in the past, and there's nothing that I can do about it. My last chance to get funding lied with STEP. Two years ago, I wanted to use STEP to do a study abroad program in France. But last semester, when the time came for me to apply to a program, I was overwhelmed with anxiety and doubts from my parents and myself in the benefits of going to France, and how much money it would cost. In short, I didn't end up applying, so I had to redo my STEP proposal. For the last two months, I worked with my thesis advisor on reformatting my STEP proposal for the undergraduate research category. I included information about my plans to travel overseas. I worked so hard on the proposal and I was very proud of it when I submitted it. Today, STEP emailed me, saying that they wouldn't fund my project because I'm going overseas. It's my fault for forgetting about their travel policy. But I wish they could have given me something to help my parents out. The cost of this month-long trip is considerably more than the study abroad program, yet my parents are still going through with it. On top of that, I am taking two summer courses that I need to graduate on time, which my parents are also paying for. I just feel so bad, especially since this is something that has no immediate return on it, if anything at all. They're funding something that I just want to do, not something that is specifically necessary. At the same time, I view this project as something that could be really valuable to me personally. So, I still want to go through with it. I'm incredibly grateful and very fortunate, but I am overwhelmed with guilt for this privilege, especially since I'm aware of the other funding opportunities that I missed because of the early deadlines. I feel like I am just draining my parents bank account and all I can give them is a promise to pay them back in a few years.