Ether is safe, but like other bitcoins market rates go down and up quickly. There are times where you need to buy the crypto itself to actually earn something.
If your talking about Computer safety, your wallet is as secure as your device. This kind of wallets are based on public and private keys, il you loose both of it you will loose your money. Mys first advise, always add a strong passphrase on you private key ! My second and very IMPORTANT advise : Never use online wallets !!!!
