New to ancient coins: how much liquidity is there and what is the recent valuation trend?

I'm rather new to collecting ancient coins and tbh this os my first true "collecting" hobby.

I'd like to look at this as an "investment" approach, but I have no idea how I could sell my coins if I had: how long it would take to sell and if I'd see my money back, make a profit or lose money. I also don't live in the US, which from my understanding is the biggest market by a mile.

Also as a side question: I see a lot of fluctuation in coin prices, but the recent Triton auctions in CNG got me thinking we might be in a bubble (though I have VERY FEW datapoints) - I actually got my first serious coin from there and although I feel like it was a bargain compared to other coins, in absolute terms it was a massive expenditure for me.