And when, not if, your controls and contacts in your vintage receiver, amp, preamp, turntable/cartridge, even speaker connectors get corroded and they require a good cleaning and service, you can pay a tech to spray probably the same product and spend your money that way. Sure, there are a lot of good contact cleaners out there too, and some are less expensive, some may be reasonably or just as good.
But DeOxit has developed a pretty good track record with professionals and amateur / DIY users alike. That experiential results have fortified the DeOxit reputation makes it a reasonable and reliable recommendation, and for some, paying for a good useful tool is well worth the few extra dollars and cents. IME, a can of DeOxit has already lasted 15 years even with judicious use. Heck, I may even still have some Cramolin around somewhere. I was gifted some D5, Pro Gold, and Fader Lube as well, and they are an important part of my audio as well as general electrical tool box.