If my mom gives me 1000 dollars for 1% of my lemonade stand, that doesn't mean my stand is worth 100k. Tether is in talks with investors to mayb raise 20b at a 500b valuation. Keep in mind also that crypto investors overvalue companies to create the hype and then lobby for better regulations etc. It doesn't mean at all that someone would be interested to buy 100% of tether for 500b. Now, if they were public is a different story, like Tesla etc