Please take this with a large (more than twice-your-age-Gen-X sized) grain of salt … not really atuned to your generation and so probably not really providing useful commentary for you. 
Just echoing what @rolandinho has stated already: I am amazed how sensibly you are thinking about these things are your age. Congratulations on that achievement already!
I was pretty smart at your age but super dumb moneywise. Like nowhere near the level you seem to be at.
You seem self-aware and smart moneywise.
I hope you don’t perceive this particular comment as patronizing - all I want to say is that I perceive your perspective as pretty mature, much more than mine ever was at that age.
I would not have the guts for this kind of (concentrated) diversification.
I know people (like Buffett et al) say there’s higher returns with more concentrated portfolios, but there is also higher risk. If you can afford the risk, fine.*
Your company 1 and 2 investments are the most eyebrow rising to me. In your position I would probably not diversify this into the hundred+ companies as I did (since I can take less risk and you can take more), but distributing more than half your total assets into just two companies would make me very nervous.
That said …
(a) you seem to know these companies and can probably better qualify your risks versus a broader market,
(b) perhaps these companies themselves are really well diversified for their returns,
(c) you have enough substantiated insider info that these companies will do well
… that you’re comfortable with that asset allocation.
If I were you at my age (impossible, I know) I would diversify your company 1 and 2 holding (assuming they’re liquid at the valuations you cite) into
- (preferrably) a dividend growth strategy if you want to and have the time to look at individual companies, valuations, and a bunch more of fundamentals. I am convinced this gives you the highest returns. Details here.
- plain vanilla low cost ETFs. S&P 500, more VT, you name it, if you can’t be bothered with individual companies. I’d still recommend averaging into them (versum lump sum allocation), just for psychological reasons.
Cash position is fine as long as you don’t need a return, though currently treasuries are probably just as attractive if not better.
Crypto? Speculative … maybe? Long term, no.
* I personnally would not have the guts for more concentration until my total portfolio value reached the stage that even with a 50% total drawdown I would never even fear running out of money ever.
Probably at least low 8 figures CHF for me.
Perhaps with your current yearly expenses and your total equity, this might be fine, though?
Nice.
It’s just about what I am aiming for (income wise), but (ideally) purely from dividends.
At your stage, this allows you to “snowball” (further invest) at a very nice accumulation rate.
Given your basis, current expenses and funds available for reinvestments, you should be doing very well going forward.
Congrats again.
I understand your concern, though I’d look at it from a liquidity perspective.
The funds held in custody at any broker will always be yours. When you get them in a bancruptcy situation it anyone’s guess, but you’ll get them eventually. Question is whether you’ll get by in the mean time.
I would not have any issues with holding all my assets at one broker as long as my guaranteed cash flow (from other operations) would cover my expenses (which appears to be true in your current situation).
Oh, and I am sorry you lost money with FTX, but comparing FTX to IBKR seems like comparing, ahem, say, Coinbase to Treasuries, in current market situation terms? One thing ain’t like the other, stability wise.
I’m afraid I cannot really offer much advide on either issue.
Owning or building your dream property is something I would pursue given nearly infinite funds. Given my finite funds, I have the same reservations you already have.