You "remember" wrong. I actually _was_ there. Neglect and price of oil weren't in any way fatal to a largely self-sufficient country. Complete collapse of all branches of the government was.
The empire certainly wasn't self-sufficient, although the Russian center was richer. The empire depended on very large-scale oil exports, to subsidize the bloc. Even with those exports, the line-ups for basics was real in Russia, too. Russia's self-sufficiency isn't much in evidence today, either, as the economy shrinks year-on-year, and three-quarters of a million of the most capable people emigrate each year.
It didn't help that the US did everything it could to drop the price of oil specifically to destroy the income source of the USSR. USSR is too dependent on that single income source and left itself open to attack.