No reason to upgrade if you don't plan too stake or move coins. Just upgrade the next time you need too move coins.
it's a mandatory update but as long as you have your private key(s) your are fine. If you don't plan to send coins and you're not staking them you don't have to update anything. Every wallet works this way.
Anyway, for all the others: Update your wallet guys!
His question was whether he should update if he plans to hold only, the answer is no. Not everyone is able to stay on date with all the update we have.
Devs: This is a mandatory upgrade.
JJack@: ok
JJack@: Thanks, it took 2 minutes and my coins are now safer!
You seem to lack basic understanding of how DeepOnion (bitcoin) works. There is a lot of good arguments why you should upgrade. That the coins are safer is simply not true. Your coins are much safer without an upgraded wallet installed on your computer.
If you plan to hodl your coins you should encrypt your wallet.dat, and delete the wallet from your online computer. (And only install when you plan too send the coins. If he wants to send the coins 2 years from now, there will problably be a lot of hard forks before that. It is a complete waiste of time installing every upgrade and it is risky storing private keys on an online computer.
Unless we know what security risks were patched, it is difficult to say that this fix did not make our coins safer.
You are right, 10% of PoS rewards (which will change to 5% in July and later to 1%) is not a small percentage for holders. Also, updated wallet which is online is a ToR node (not an exit node) which makes the whole network stronger.
Most people should definitely upgrade and stake their coins. But if someone just wants to hodl, like bbv4pawn, it is not necessary. And that was what he asked about.
Big holders will upgrade and stake their coins. If some smaller holders don't it will not reduce the security of the coin in any signifcant way.