I am using a web-based wallet Blockchain, I am sure you have heard of it.
The thing is I trust trusted this because it is a genuine company and I can generate a paper wallet also through it.
But now I think I have to upgrade to the Desktop wallet.

Yes. There are a lot of user complaining about that, and there is some couple of cases that someone's account got hacked, and they even tell their story on this forum. It is indeed a scary story.
But one thing for sure, you should be scary about anything that can threaten your bitcoin even you only have a little, do not start to worry when you already have a lot of it.
In my opinion, the best and most comfortable way to secure your bitcoin is using a hardware wallet. There are some that quite popular, like Trezor or Ledger Nano S. If you can have a lot of bitcoin, you shouldnt have a money trouble for buying this kind of wallet.
You should not focus for searching the answer for your last question, as none you can do if that happens. The best way is prevention, before it happens.

Even if  you have little or lots of BTC, you should be afraid of hackers and secure your wallet. It's your hard earned money/investment and you should be the one who enjoy it's profit and not the hackers.

Yes you should be scared of the hackers only if you are not good at managing your account for security purposes. If you know how to manage them very well and you know how to avoid getting hacked then there is nothing to worry about the security but if you are really concerned of the security of your bitcoin then having a hardware wallet is a good relief for you.

Security would be the main concern on here on which each wallet holder should really be responsible off on keeping their keys or informations that are important to access the wallet.Once its being kept on the right or secure place then i dont see that we should worry bit too much.If its keep from others awareness then you would be always safe the thing you should be aware is on the possible ways which hackers would lure you in. Like phishing and malwares.

As long as you store your Bitcoin in the safest wallet like trusted online wallet or offline wallet maybe it might be protected.  And also do not use it for other things related to transactions on some sites because hackers have many ways to get what they want.

I will try that.
Thanks.

If you really have a lot of bitcoin you should be careful in choosing your wallet, you should use offline wallet instead of using those web based wallet it's much safer that way and just be careful don't give your private key to anyone.

Donate it to all poors, then you could sleep well every night.
There is no way to be 100% safe in the world unless the god bless you.

Today bitcoin is on the hotspot of the hacker. Maybe we should be worried about our bitcoin wallets but being scared is an exaggerated. Hackers are already their, even government sites have reported that they are hacked by hackers, meaning to say its already happen so if we're gonna be scared then we can't think the better solutions to just avoid our wallet for being hacked. We should be aware and keep our wallet secured enough.