It is undeniable that a Constitutional Convention would be an easy way for a dictator to seize power. If you get, say, twenty-six delegates in your inner circle elected, assuming each state elects one delegate, you could easily become an absolute monarch.
But 3/4th of the states would have to ratify those amendments. It would take very wide consensus for a dictator to seize power.
Theoretically, they could suspend that rule.
How?
The people on this forum screaming about how "Con Con II" will be the end of the American Experiment need to calm down. There is no way a constitutional amendment could get passed anyway, since you can't get 38 state legislatures to agree on anything anyway