You may have meant 'domain' as in an area of interest, in which case this is good advice. For years though, I was a proponent of the 'buy a domain name first' method of idea validation. As a result I spent far too much time and money on domain names when I should have been testing the idea/market.

Thanks for pointer. Quick summary of my historical interests: breakdancing -> Finance/investing -> automating stuff with code -> software projects -> cryptocurrencies -> functional programming. The domain I have invested in (probably will for another 3+ years or even more): cryptocurrencies; there is a lot of hype right now but I have been following the space for a while and my interest hasn't decreased and that's certainly not due to the prices. That's why I'm searching/exploring further.