Based on Acemoglu & Robinson's Model
Acemoglu and Robinson's model suggests that democratization is most likely at moderate levels of economic inequality. If inequality is too low, citizens may not have strong enough grievances to demand costly political change. Conversely, if inequality is very high, elites stand to lose too much from democratization (e.g., through redistribution) and will therefore fight hard to prevent it, often resorting to repression. This can make authoritarianism more entrenched or increase the risk of revolution if democratic avenues are blocked.