Anyway, the decline and fall of the Roman Empire has been a source of after-dinner discussion for at least 400 years..... it certainly exhausted Edward Gibbon, who died only two weeks after he finally saw it in print.
Michael Grant pushed taxation as a cause. Others like trade imbalances with India better (depletion of cash in circulation) .... and of course some people blame Christianity, or the reorganization of the Roman army, or what do you like.
Sure had.
Considering the fact that the Roman Empire lasted much longer than any other great empire, 700 to 1700 years, depending on how you figure it, a more logical question might be to ask how it was able to last so long before it finally fell.
As stated, my personal opinion is the lack of an ideology to establish who had the right to be the next emperor. This had horrible consequences not only at each accession, but in between.
Most Roman emperors who founded a dynasty came to power by coup or civil war. Every reigning emperor therefore could never fully trust truly competent and ambitious generals, as he had to always remember their potential to displace and kill him.
This is in considerable contrast to the primogeniture monarchies of early modern times. Louis X or Henry VIII never had to worry that one of his generals would replace him on the throne, as nobody would follow such a usurper. When the King died, with rare exceptions everybody knew who the next king was and loyalty usually went to him without a pause.
This didn’t prevent dynastic conspiracy and civil war, but even then it was limited to members of the royal family, not a total free-for-all as in the Roman Empire.