I have used a menstrual cup for decades. Yes, they change colour, but that doesn’t change their structural integrity. **I have the same cup I bought originally, and it’s still going strong.** The brand I bought had numerous people who had been using their product for a very long time, and were yet to find one that needed to be replaced, from memory. I honestly believe that if you buy one when you are young, you will still only need one for your whole life. But I haven’t tested them in a peer-reviewed scientific study!
The only thing to really learn is how to insert it properly – it sits in a different place to a tampon, and you need to fold it to get it in, then let it pop open by itself. (If you don’t insert it correctly, it can fail to work, obviously.) Depending on the brand/design and your own body, you might need to shorten the stem that you use to remove it (i.e. cut off a bit of it so it doesn’t sit outside of your body once it has been inserted properly). The other thing is that sometimes it can feel like it’s leaking when it’s not – it can take some getting used to the sensation and not panicking that it’s not working.
Call me gross, but I don’t boil it between cycles – I just rinse thoroughly with hot water and leave it to dry. Yes, I’m only one person, but I have used it continually for decades now and have never had issues. Just like tampons, if you leave it in for too long, there is a risk of Toxic Shock Syndrome, but given that only the silicon or rubber is in contact with your body (and not the blood collected), I think the risk is much reduced over tampons.
I used this extensively whilst living and/or travelling in developing countries, where it was hard to stay sanitary (countries like Tanzania where toilet paper is really hard to come by) and even then, I never had problems with TSS. I just tried to make sure my hands were more-or-less clean (no visible dirt), but I wasn’t hypervigilant about it. In a pinch, I would drain it out and then re-insert it (if I couldn’t clean/wash it at the time). That’s NOT recommended, but I’ve done it a bunch, with no adverse outcomes. It was far superior to disposables, because those countries also don’t have waste management – so I would have been giving them rubbish problems otherwise.
Before having children, my periods were exceptionally heavy. I found that for the first night, and sometimes the second, it was worthwhile having some form of back up in my underwear, and making sure I went directly to the bathroom as soon as I woke up. But, I was unusual. And the cup can retain far, far more than a tampon ever could!
Using a menstrual cup is my #1 piece of advice for saving money for women, too. You buy it once (and have one or two reusable menstrual pads as back up if needed) and never have to buy menstrual items again! Brilliant!