You stop them by having better ideas.
Those better ideas must also be placed before the youth. Conservatives need to become teachers in all of the school systems. Conservatives need to become administrators in all of the school systems. Conservatives need to raise their young ones themselves. Conservatives need to become members of governing bodies as well as employees of government agencies.
They need results. They need a path to the middle class. They need to be able to buy a home, buy a car, see a doctor, earn a pension.
Too many young people feel that they will never be able to afford the lifestyle their parents had and yet they look around and every brown person, every illegal immigrant, is already enjoying the fruits of socialism with their free homes (Section 8), free health care (Medicaid), free food, (SNAP, WIC), free walking around money (EBT, TANF) and countless other government gibs we hardly even know about.
They're starting to say, "Well, If I'll never be able to afford a home, why don't you just give me one like you gave Faisal and Shaniqua."