The purpose is to serves as an intermediary between two people due to trust of the service. Escrow person will have its own terms and conditions to make sure no one got scammed, both the buyer and the seller will also have to comply to the terms and conditions. If done appropriately, the buyer, seller and the escrow person will not be scammed which means no one will be scammed.
Not for nothing, but we didn't need a mini-essay on what an escrow service is. If you don't have an opinion on this matter or are unfamiliar with it, just don't bother with bloated shitposts.
Shouldn't be an escrow need to have enough money of his own before performing an escrow in a marketplace?
That would be ideal, and I wrote much the same thing in the thread dealing with the charity:
Frankly, if you're going to be holding funds for a charity or anything else that requires you not to dip your hand into the cookie jar, you really should be financially well off enough such that you wouldn't need to.
Unfortunately, how many of us know the financial situation of any other member on bitcointalk? Very few of us know each other in real life, and if someone is offering an escrow service, how is anyone able to determine whether that person is in financial trouble? They might have a bunch of green trust, they might be on DT, but none of that indicates how well-off they are or if they'd be tempted to scam if they had control of a large amount of funds. Again, I'll give the example of
Master-P who was very trusted but wound up scamming for a lot of money. You just never know.
I think there must be an impeccable reputation, also a user running his escrow service would have to show that he owns the same amount which he will hold as a third party. there is probably less possibility that he will use funds from escrow for grandfather's treatment (just example).
That wouldn't guarantee the escrow wouldn't be tempted to double his money, though. Even if the escrow provided proof that he had 10x what he was escrowing, temptation, the irreversible nature of bitcoin, and the history of scammers not being brought to justice might still be temptation enough. The fact is that trusted members have scammed before, and people have been scammed for relatively small amounts of bitcoin before. Those things will no doubt happen again no matter what safeguards are in place.
So yes, an escrow--at a minimum--should be financially well-off but I don't even think that guarantees they wouldn't scam. I honestly don't know what can be done to ensure the safety of someone's funds with an escrow other than if the escrow has a long track record of successful escrowing, and even then....