Since most of the democracies determine the result based on first past the post (FPTP) or closely related voting system, the candidates only need to get 50% of the voting population to agree with them. They focus on populist policies that resonate with at least 50.1% of the population even if those policies will be detrimental to the remaining 49.9%.
The opposition is not seen as strong enough to lead the country. This was the case in recent Turkish elections and has been the case in the last 3 Indian elections. Erdogan and Modi keep winning because people who don’t want to vote for them are not convinced by the other candidates’ abilities to lead the country. So many of the opposing people don’t vote at all or have their votes fragmented across multiple candidates in FPTP systems. That was and also remains the concern with Biden in the US.
Once these leaders are in power, they actively suppress the voice of the minorities, by controlling the media and law enforcement, or by making it harder for minorities to vote and express themselves. This reduces the total voting population in favor of these leaders which again benefits them get past the 50% votes. Ultimately, we observe the vicious cycle of more power consolidation over time and more authoritarianism.
Some other factors that I have noticed -