Blockstack wallet sequrity

#1

Why did blockstack use word phrase instead of private key. I don’t feel very comfortable when I have to type seed phrase on a Windows computer. If someone get a virus it can be stolen. Yes I know there is ledger support but on pre-register I don’t know if there was a wallet with ledger support so now all my monthly reward go to my wallet which not have ledger support so I have to transfer it over to my ledger.

My question is how do I make my seed phrase wallet safe? I don’t understand why I have to enter the word phrase also when I want to send STX. I am to afraid to use the wallet because it can be stolen while sending it. Please let me know if there is any solution that will fix this problem. One more question is there any wallet that has Linux support?