The hoarding stopped in November when a gardener stepped on chemical residue in Jakubec's backyard, suffering eye, chest and arm injuries.
Authorities destroyed the home in a carefully orchestrated burn that played out on television screens across the U.S. in December.
The former software consultant faces a maximum sentence of life in prison when he is sentenced Monday. Prosecutors are recommending 30 years.
The immigrant from former Yugoslavia pleaded guilty in March to brandishing firearms while robbing or attempting to rob banks.
In a plea agreement, Jakubec acknowledged making and storing explosives and weapons at his ranch-style home in Escondido, including nine detonators, 13 grenade hulls and large quantities of the highly unstable Hexamethylene triperoxide diamine, or HMDT, which can explode by someone stepping on it. He also admitted having significant amounts of Pentaerythritol tetranitrate, or PETN, the explosive used in the 2001 airliner shoe-bombing attempt.
He agreed to reimburse San Diego County the $541,000 it cost authorities to destroy the home.
Letters to U.S. District Judge Larry Burns from Jakubec's wife and others portray a man who was despondent about losing his job in his early 50s.
"George told me that unemployment makes him feel useless and worthless
-- a terrible feeling for a man who worked hard all his life and was successful and well-liked at work," said Ivanova, his wife of 11 years who met her husband on the Internet and moved from Russia to marry him. She called him a wonderful, loving husband.
Jakubec came to the U.S. in 1971, when he was 15, according to cousin Paul Abelovski. He attended San Diego State University and worked for computer maker Burroughs Corp. and information technology company Unisys Corp.
Jakubec excelled at work, William Jasper, a former co-worker at Burroughs, wrote the judge. Later, he got a general contractor's license and built and sold upscale San Diego-area homes.
"It seemed that sometime after the turn of the century George's career ceased to flourish," Jasper wrote.
Jakubec pleaded guilty to brandishing a firearm while he robbed a Bank of America branch in San Diego of $42,012 in November 2009 and returning with a firearm to the same branch two weeks later in an attempted robbery that was foiled when he spotted a security guard.
Jakubec acknowledged in his plea agreement that he robbed other Bank of America San Diego branches of $1,480 in 2010 and $10,400 last July.
As part of the agreement, prosecutors offered to drop charges of making and storing explosives and robbing the banks.