The Republican party lost with squishy McCain, Dole and Romney, instead of the strong conservative the base wanted. They only one with Bush 2, and half of that was name recognition.
This shows that the candidates the Republican party elite likes are LOSERS.
And that's why the party base needs to essentially ignore the party leadership, because it is not capable of winning - and Trump is. In fact, he's attracting the traditionally Democrat working class vote - black, white and Hispanic - focused on jobs lost to outsourcing and taken by illegal immigrants and visa holders. The Democrats ignore them because they want the new socialist leaning immigrants as voters, existing people be darned, and Republican leaders worship free trade and low cost labor so much they ignore the people hurt by it.
Then you get the ghetto-ization effect, where someone rides the bus and never hears English, and it is easy to feel like you're losing your country, your identity is demonized, wearing a flag shirt is racist - and the elites celebrate "diversity" while ignoring the crime, poverty and problems this causes. They feel good about it in theory, and they're ignoring the harm their policies cause - and that's why people are angry and Trump is getting their support across all races and party lines.
Then you get Democrats focused on ever more bizarre sexual freedoms, instead of real world problems like safety, jobs and the security net that so many are focused on. Let's argue transgender rights when 15% of the workforce has stopped working, shifted to early retirement or SSDI or given up.