It costs $1 to increase the market cap of a fiat pegged stable coin by $1, while changing the market cap of Bitcoin is a lot cheaper because there's no safe way for a market maker to provide substantial liquidity for it. At any time this dynamic can start working in the other direction, and the market cap of Bitcoin can fall below the net value converted to it.
Well, no, it costs absolutely nothing to print off another billion Tethers. We only have the vaguest possible assurances that there's something behind each USDT, and they've already admitted it's not actual dollars.
I don't really know what you're saying. It's not much less safe to provide liquidity to bitcoin than to do so for any of the trillions in securities priced vastly in excess of the book value of their underlying assets.
