tether
Yes. Most people are into bitcoin as a way of investment. An investment that yields more than stocks or gold. They no nothing excpet bitcoin.
Like the user above stated, they used to sell bitcoin to buy alts when the prices of bitcoin started to decrease and buy back when it stated to increase but with the introduction of stablecoin, people find it easier and safer to convert their bitcoin value to stable fiat value.
I would not want to believe that it is tether, the reason why people put in altcoins is strictly for investment just as the way they put money I bitcoin too, just that during the last time bitcoin increased, people still trusted altcoins and they usually pick interest in both of them anytime that they desire to invest, and they would have still used tether even if they were making investment for altcoins too.
The reason why we have seen such drastic decline in the altcoins industry is because investors are skeptical about altcoins investment nowadays because it seems like many of the ones that have committed their money into end up going below what they invested in without hope of rising because of the weaknesses of the team, or they probably get scammed.