They won't. This looks like a covid 'investment' coming back on to the market.I can't imagine the seller getting any near that sort of money now, possibly during the covid era maybe.
That's a reweld, or at the very least a precautionary bead of weld to shore up the signs of cracking. The 1991 bikes were notorious for cracking around the head tube area. The following year there was a gusset added to avoid this issue.Top of the down tube doesn’t look right to me.
The 1991 bikes were notorious at cracking around the head tube area