BTC to bytes: 1 BTC of proven balance gives you 62.5 MB (0.0625 GB)
My first time here 
Do I get this correct: 1 GBYTE is currently worth $70.70, so owning one Bitcoin gives you $4.42?So someone who owns thousands of Bitcoins can cash in quite big?
Yeah that is the downside of the distribution of some airdrop in my opinion. Only the rich people can become richer especially those giveaway that is based on the BTC holdings in their wallet.
Looking further into this, I don't think the "value" says anything: it's 24h volume is very small, and only one very unknown Polish exchange offers trades. It doesn't seem to work properly either.
That being said: some airdrops in the past have been very profitable for people joining them. Get coins, keep them, wait, and if the altcoin gets pumped very high, you can cash out! That brings me to the next question: how to keep those wallets? I'm now using VirtualBox for ByteBall, I don't want to run unknown software on my system. If I add 10 more like this, these 10 VirtualBoxes with almost worthless altcoins eat up more space than the entire Bitcoin blockchain. My laptop doesn't even have that much space left.
What is a good way to keep the wallets without any risk of compromising my system? It wouldn't hurt to join some airdrops just to look back at the wallet a few years later.
I would advice to move to the light version of the wallet (you need to move your funds if you're currently using the full version) and then use the 'full backup' function. This backup can be compressed and encrypted and can be stored easily, e.g. on a cloud service. For a light wallet the backup file is a lot smaller as for the full wallet. Keep the password for the backup somewhere safe.
As a fall-back option, write the 12-word seed of the wallet on a piece of paper or in your password manager. Please take notice that the seed can bring back your bytes but not your blackbytes (due to the private nature of this asset it's technically impossible to restore your blackbytes from the seed alone).