In general; I think even 2 billion is too much. Nobody needs that much money.
At best; I think no one should be able to have more than about 500 Million. You get one house, and one car for each adult family member if you’re married with non-adult kids. Adult kids don’t add uncounted vehicles; they have their own limit. Anything that is seaworthy or airworthy counts as about as much “Wealth” as you initially spent on it minus a reasonable depreciation rate yearly as determined by the market, so no buying a thing and having it lose 30% of it’s value the moment you drive it off the lot after buying it.
Additionally; to block too many shenanigans; wealth added by any property that is bought sticks; 3 years at minimum. This prevents people from storing too much excess in property and shell-gaming it. A company you own or have stake in cannot lend (in a long term) or gift you property in excess of 1% to 10% the wealth limit. (Depending on what the thing is). Companies may also not hold property or money in lieu of an individual personally; everything the company owns must have a global company function; and not personally benefit one or more people only. (Basically no executive-only or owner-only Jets; everyone from the tiniest manager on up should have access to it if there’s a business reason for it)
Keybase is better than Signal. You may not like it’s current owners but it still works, still functions, and can be used to chat privately. It’s entirely OSS on the client side; and server-side software isn’t provided; but with an open Client; it’s likely trivial to reverse and re-implement your own. (Keybase itself doesn’t provide their server code; it’s private due to abuse constraints)
Keybase is End to End Encrypted. It may not be as “feature rich” but all features are private.
I’m not sure if it’s indev anymore though; and it does allow you to be as public or as private as you’d like to be about your identity.