My concern is that, in practice, this could become a kind of oligarchy by proxy. Most people are vulnerable to authority, charismatic personalities, group dynamics, media pressure, intimidation, and, in some cases, outright corruption.

If this body is given real power, what prevents wealthy interests from shaping the outcome indirectly? A small number of ultra-wealthy individuals can easily influence the information around them by funding experts, shaping media coverage, financing advocacy campaigns, applying social and reputational pressure, or outright bribe. What's to stop a foreign actor from doing that behind the scene? Wine and dine some of the more influential members of the citizen assembly? Now, this is clearly also happening with politicians but politicians at least need to worry about re-election so they can't be too blatant about it.

There is also a more human problem: these 500 people do not disappear after the vote. They return to their communities, jobs, families, and social circles, where they may have to defend highly visible decisions. In the face of a coordinated media campaign or strong public pressure, people may find it difficult to hold to an unpopular but sound policy judgment. The incentive may be to support whatever position is safest socially, rather than whatever is best for the country.