You're an incredibly ignorant individual. USSR was never allowed to develop peacefully. It was invaded by western powers in 1918 right after its formation, then it was plunged into WW2, and after that the Cold War. Saying that the fall of USSR was squarely caused by themselves is the height of idiocy. The west forced USSR into spending incredible amounts of productive power in order to simply to be allowed to exist. It's also worth noting that the collapse was in no way inevitable, and largely a result of Gorbachev's privatization and liberalization policies. The west was also directly involved in propping up Yeltsin and suppressing communism after Russia opened up.