The owner of the garage used for Banksy's most recent artwork said he has been in "freefall" since it appeared and is struggling to cope with the responsibility.
The mural appeared on steelworker Ian Lewis' wall in Port Talbot a week before Christmas.
Mr Lewis, 55, told BBC Wales he now needs help to find a long-term solution for it.
"It's been very, very stressful and very surreal," he said.
"It's just all been so much for me. I'm actually managing an arts attraction by myself.
"There's in excess of one thousand people going there a day, all hours, day and night. I just can't cope with it now, to be honest with you."
Mr Lewis said if it hadn't have been for the intervention of actor Michael Sheen, who offered to help pay for security over Christmas, he would already have lost the art through vandalism or theft.
"I didn't know at the beginning it was a Banksy, I just thought it was a fantastic bit of artwork, and I was going to cover it and protect it and keep it for myself. Then it just went viral on Facebook that it could be Banksy.
"The first night people were coming up there and people wanted to chip bits off it.
"There was even talk that people wanted to chisel it out and take it home, they wanted to steal it.
"I've been stressed, it's dropped a bomb on me. I'd just like a bit of normality back into my life, like it used to be."
The artwork was covered in protective plastic sheeting before Christmas, but volunteers working at the site said it has still been targeted several times.
With about 20,000 people understood to have visited the Banksy over Christmas, Mr Lewis said he wants to see the garage wall cut out and moved to a safer location, while staying in the area.
"It needs to be put in the middle of the town centre maybe. They can be moved, I know they can be moved. I think it would need a team of experts to move it from what I can gather," he said.
"I think that the Assembly should step in and take over, because it is an arts treasure, and it's just too much for me."
Sheen added: "At the moment my biggest concern is for Ian.
"It's been a really stressful thing for him and it's put a lot of financial burden on him that nobody else at the moment is helping him with. I've done what I can but we need a long term solution in place.
"It's wonderful that it's there and it's great that Banksy came and did this and has drawn attention to Port Talbot in this way. But Ian does need some help with this now, and I hope that it can stay in Port Talbot."
Because the artwork is on private property, Mr Lewis is currently responsible for keeping it safe and managing the thousands of visitors.
"If I could turn back the clock then no, I was happier I think before it happened. I just don't know where I'm going with this," he said.
Plaid Cymru AM Bethan Sayed, who chairs the Assembly's culture committee, called on the Welsh Government to purchase the piece.
"Obviously this would have to be with the owner's consent - this is private property," she added.
"If we want to protect it, if we want to keep it in Wales - then we need to have it as a national asset."
The Welsh Government will see what can be done to protect the artwork, First Minister Mark Drakeford has said.
Speaking at his first press conference since taking over from Carwyn Jones, Mr Drakeford said he would ask culture minister Lord Elis-Thomas to pick up the issue.
He said: "I'm going to do is to ask Dafydd Elis Thomas to see what can be done, probably not directly but through the organisations we fund in those fields, to make sure that no undue harm comes to that new piece of art we've been able to enjoy."