In the UK we combat that by strict regulations on money spent influencing voters. Sadly, despite proving Brexit campaigns were backed by an excessive amount of money routed through a Russian oligarch the result remains (unintended ironic use of 'remain'!).

Democracy can only work with probity. If the people don't know the truth they can't vote for their choice.

Benevolent dictatorship seems likely the better option, just choose your dictator carefully!