Having a wallet or using an exchange to hold your crypto

By and large, the consensus I see online is that if you plan to have significant savings in crypto, it is recommended to store it in a cold wallet. A couple of things about this make a bit worried and I'd love for people to help me decide if it is the right move for me. I currently use Coinspot (AU) and Phantom. I want to DCA main coins for a few years. I'm worried that if I get a wallet, that it might malfunction or become faulty. Some are very flashy with touch screen interfaces and I'm almost reticent to get one because they seem like any other device that's designed to break with use. I'm also worried about losing it. If it's lost then it's lost forever. Where do you store it? How do you keep it safe? I like having my crypto on the platforms I have because I can log in to them for either my phone or laptop. How do you safeguard physical wallets?