It’s hard to engage genuine experts in a public community.
Which is a shame, because this is the audience which could offer the most value to other members.
The problem is usually simple; the community doesn’t offer enough value to top experts. Points, badges, and gamification appeals to a very narrow segment of any audience.
In my experience, top experts typically want a few very specific things:
1) To improve their expertise by gaining exclusive access to the organisation.
2) Access to other experts in a private, exclusive, environment.
3) Increase the size of their following and control over that following.
This is why at the highest levels, experts prefer either private WhatsApp groups, zoom meetings, or to post content on platforms they control.
If you want to engage top experts, you need to offer the above. Provide support to verified experts with direct access to members of your team (not just the community manager). Create and host private working sessions (in person is ideal). And link to the preferred channels (twitter, blogs, medium etc…) of top experts in your community providing they keep participating in the community.