But what makes Bitcoin price go down
As the spread continue people start to panic with the disease not Btc, thinking of many Negatives and some people exchange their Crypto to friendly fiat money so they can cover some emergency staff buys extra food, drinks, masks, etc, the simple view is that many sell result to cheapest sell which automatic kill the prices of an Assets.
The amount of people who sell their coins to cover their needs is negligible, what happened is that whales/speculators dumped their coins because of the panic on the stock market. So, coronavirus is actually the reason, it's just not a direct reason. Instead of coronavirus -> Bitcoin we have coronavirus -> stocks -> Bitcoin. But this correlation isn't fixed, if the stock market falls a little then Bitcoin doesn't care - it's not repeating every single move.