I wish you'd post proof of the collateral's existence or even addresses of those coins. Nobody can steal those coins using public addresses alone. Refusing to provide this proof is suspicious enough. It's as if you didn't anticipate anyone here would insist on seeing proof even if you offered to use escrow but now that they did, you are trying to justify the part about not providing proof of this collateral by saying escrow can do their own checks and balances before proceeding with the actual lending of BTC or ETH.

If you really have that collateral and genuinely intend to use a trusted escrow, then I guess my assumptions are unfounded. If you do get PMs from newbies offering to give you this loan, be very aware of something called the collateral scam. Do not fall for it. You will be asked to send collateral first (upfront) or to a fake escrow. By fake I mean a phished or cloned profile of an existing trusted escrow. Always verify the agreement and arrangement with the escrow directly. Contact the escrow on their official page or profile.