I don't think things like debt actually make people more conservative. I think that effect has to flow from things which actually impact peoples lives - so if the government takes on too much debt, and then cuts public services to manage that debt, which makes people feel more economically precarious, then people will statistically become more conservative. But if the debt isn't impacting people directly, then it isn't increasing conservatism. Instead, existing conservatives are predisposed to care about increasing public debt and see it (rightly or wrongly) as a threat to their way of life. But if conservatives constantly talk on the internet about how increasing debt is going to collapse the government, then more neutral people might feel threatened, and will start adopting more conservative stances.

As for what caused the shift towards Reaganomics - I'm sure we could come up with a just-so story. But I don't know if I'm the one to do it