Canada

will gain votes away from other parties.

That doesn't necessarily mean that party is diluting its principles...it can also mean that the voters in question are actually changing their minds on some issues.

And in Alberta, there have been times in the past where the PC government was unusual among PC governments for actually kind of living up to the "Progressive" part of its name.

It is weird that their getting some wealthy voters(and the PC's are retaining some least-wealthy voters)but as we have often seen, votes don't always choose based strictly on what you'd think would be their natural class interests(in Quebec in the 1960's, the Ralliement Des Creditistes-the Quebec branch of the federal Social Credit party-were quite popular among some of the poorest people in Quebec, which seems strange, because the Creditistes were deeply hostile to expanding the social wage, were anti-union, and had little interest in redistributing wealth. In that case, the Creditistes took the votes of poor Quebecers because many of them were ultra-traditionalist Catholics-the awful "every Jew who ever lived is to blame for the Crucifixion" types-who voted for that party in 1962 and 1963 because Vatican II was happening at the time and voting for a party led by a right-wing antisemite like Real Caoutte-a guy who actually once said that Hitler was his hero-was a way to express protest against the fact that the Church was embracing some social modernism and giving up some of their beloved old hatreds.