Your impressions of Reagan and his effects on the Soviet Union are inaccurate. Economically it was going to fall apart internally sooner rather than later, politically it was impossible to hold together after the cover up surrounding Chernobyl.No matter how weak the Soviet Union was NOBODY in power gives up power. There were lots of contributing factors but Reagan's agendas were a factor. star wars defense, tear down this wall, 500 fleet navy etc. we won.
Harding or Buchanan could have been President and the USSR would still have imploded.
Reagan, as Cutlass mentioned, actually strengthened the position of the ultra-conservatives. Especially SDI gave them all the reasons in the world to double down on continued stalemate.
Reagan was oblivious to the implications, and blindly insisted that they had nothing to worry about, against the analysis and recommendations of his professional foreign service officers.
Reagan, if anything, prolonged the cold war by a year or so.