Even we keep saying and keep on the note that we do not recommend putting your seed phrase in the internet still there are people who will still do the same thing like with this guy did,
No matter how much we harp on about it, its of no use if these people dont read this forum (or other sources of information to boost their expertise regarding cryptocurrencies).

though at the first place its a large amount of money so why they are too much careless with this,
Perhaps it is because these people are naturally so carefree and irresponsible? Just look around, we are surrounded by many people who commit extremely foolish acts, and not only when it comes to finances.
tons of people do all of the possible attacks as they can just to steal your money.
Crypto industry breeds paranoia among
BTC-owners.

Imagine they have a lot of money to buy a hardware wallet,
I don't think having $245 million is enough money to buy a hardware wallet (though it is enough to buy the manufacturer of hardware wallet).

Owning a hardware wallet certainly wouldn't have saved this cryptocurrency owner from losing his assets, because he would have been the one to press the confirmation button on the hardware wallet for the transaction sending funds to the attackers. People like that should hire a trusted expert to manage their assets, since, as this story shows, they are simply incapable of doing it themselves. By the way, how did this owner acquire 4,100 Bitcoin with that level of competence? Just a lucky guy who managed to buy in early?
and diversify
They are unfamiliar with this word - let alone the principle behind this behavioral investment strategy.

but no they choose the easy, hassle-free way to access the wallet.
It was as if the former owner went to Google Drive every day to touch his 4,100 Bitcoin.

Why did he need such a simple method of access? Such amounts should not be touched at all for many years without special need: put it in and let it lie there (a reliable hardware wallet - or better yet, a split one), stored, for many years.
I can say it will be charge to experience.
What portion has the Singaporean boy already irretrievably spent?

But good thing the attacker caught,
Because the "heroes" in this story deserve each other. The perpetrator isn't exactly a genius, either.
does the funds back to the owner?.
That is, if he manages to explain the origin of these funds to the authorities. It would be amusing if those 4,100 Bitcoin turned out to be "dirty" or if the former owner failed to clearly prove their origin (or if law enforcement found the proof insufficient), and the assets were forfeited to the state. Most often, such news stories recount how valiant officers caught a villain, but they never mention what happened behind the scenes: the return of assets to the original owner.