You should really consider buying a hardware wallet like the Trezor or even better the Digital Bitbox to store your funds long term. They have come a long way since the early days and some of them allow storing multiple currencies at once. One wallet essentially means only one thing needs to be hacked/compromised. Are you 100% certain there's not some tiny little malware on your computer (or your phone, or even your USB-lamp) that could possibly steal your private keys or log your keystrokes?

I really don't want to be one of those people who go "Hey please look at my channel just because I left this post here", but since I wrote a short review on the Digital Bitbox hardware wallet recently I might as well suggest it for your reading list:
https://steemit.com/security/@the-tech-guy/hardware-wallet-review-digital-bitbox