You're absolutely correct, a democratic system is not overturned by a populist in the first instance - and certainly not at the point at which they're voted in - but what happens next will be interesting. The problem isn't with electing populists, it's what the populist does next. In the case of Boris here in the UK, he prorogued parliament to reduce voting time on a key bill and the High Courts brought everyone back to Parliament because it was unlawful. In the case of Hitler, Germany awarded him Article 48 privileges and he never looked back. :o)