The really valuable domain names consist of one word, perfectly describe the content of website, very memorable and can be used commercially. Examples: Sex.com Pizza.com Rent.com They ARE worth millions. All valuable domains were registered until 2000 (except for upcoming social events, brand names, movies, books etc).
Anything like 6d8.com,wcqz.com, 126d.com or even sparky.info is NOT really valuable. Even if abbreviation of a company name consists of wcqz they will find a way to register it by expanding one word moving to another domain extension etc, and will get better search rank in Google for "wcqz".
There're about 17k+ of LLL.com and over 450k+ of LLLL.com and all registered. Some dumbasses pay $500+ for domain name like that and think it will go up in value. Well, that happens if they find someone more stupid.