How safe is BSC (bep20) chain? Is it okay to store a large amount of BTC and USDT on that chain? If Binance shutdown will the chain still operate normally?
BSC is Binance Smart Chain and it is an altcoin blockchain, a copy of Ethereum EVM blockchain. It is not a Bitcoin blockchain and you can not have Bitcoin on BSC.
You can have Wrapped Bitcoin tokens on BSC but these tokens are not Bitcoin. You can see their token prices are similar to Bitcoin price but these tokens can lose their pegs to Bitcoin and prices will sink to zero.
If you want Bitcoin, buy Bitcoin, don't buy any Wrapped tokens.
https://www.coingecko.com/en/categories/wrapped-tokensBinance Smart Chain can be halted by their team and it is unsafe to use, less safer than Bitcoin blockchain that can not be halted by any team.