Gentrification policies do benefit some residents of cities in terms of economic development and safety. Gentrification restores downtown areas to a semblance of their former glory by removing some of the rot and decay. The people who are displaced by these policies are what proponents of gentrification would consider to be the "rot and decay". In the end, those who can still afford to live in the newly restored area do indeed benefit from the economic development and safety.
No, gentrification policies do not actually benefit residents of cities in terms of economic development and safety, because the improvement of a poor area of town has to happen naturally. Improving a part of town cannot be forced. If some people have high-incomes, there would be a disconnect with the rest of the people in the area.
Gentrification in the city seems to only benefit a small set of the population. It usually means that some people are goign to be excluded or given the worse end of the stick. For every person that benefits, there is probably a polar opposite where the person is being hurt.
Gentrification policies do not benefit the existing residents of the city. That's because when gentrification happens, longtime residents are pushed out of their neighborhoods by affluent colonizers, who then reap the benefits of safety and economic development. Gentrification is a toxic, racist product that destroys the heart and soul of a neighborhood.
I think the trend of, well, trending toward the rich does not work. This has been shown ever since the Reagan administration's abject economic failure. The focus needs to be on improving the worst areas first. After that, maintainence. If and when this is achieved, the rich can get the attention they don't need.