Are quantum computers actually that dangerous for crypto?

My technical knowledge isn’t that advanced I apologize. Wouldn’t it be a safe long term bet to just buy coins like QRL that are specifically designed to be quantum secure? Or am I oversimplifying it? Also is there a protocol / plan for existing cryptos to become secure against quantum computers? I heard it’s supposedly very hard for bitcoin to become quantum computer secure whereas coins like Ethereum or Solana have it easier. It’s just a thought so don’t grill me for not knowing the technical details but I’m just wondering if quantum computers might be the end of crypto in the next 10-30 years