Kate,
For the organization as a whole, that can't be predicted, because we don't know from any one month to the next how much new money will come in and how much old money will go out. Still, I love the question. Online sources tell me that there are currently 18,503,862 BTC in existence with about 900 new ones per day (this will go down over time, but I'll stick to 900/day so I don't have to look up all the rule on halving the production rate).
But, if we make a couple simple assumptions about an individual investor who makes one deposit and never withdraws until all the current BTC are claimed, the math isn't too hard.
Assume someone places 10 BTC (note that MTI claims to be trading far more BTC, so would get there sooner) and gains 10% per month. Daily compounding will yield slightly higher results, but monthly is simpler.
After 12 months, our future owner of all BTC has 10*(1.1^12) = a little 31.38 BTC in total. This isn't going well. His whole year only netted him 21 new coins and 900 were produced in a day. He now owns 0.But, he's patient.
After 5 years, he has 10*(1.1^60) = over 3044 BTC. So sad, since the world generated 9000 in the last 10 days. But, he's knows that compounded gains are how a single snowflake becomes an avalanche.
Is it possible he can ever even catch up to daily production? (365*900 = 328,500 new BTC per year)
After 10 years, he has 10*(1.1^120) = over 927,090 BTC. That's 2.89 years of total production and is 4.25% of all BTC in circulation that year, but it took him 10 years to get it. In that 10 years, (let's ignore leap years), the world began with 18,503,862 BTC and gained another 3,285,000 BTC Should he give up, or should he realize that good things come to those who wait? He decides to wait, but realizes he doesn't need 5 more years (and I realize a spreadsheet will be simpler than doing each year's calculation.
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In 12 years, he ends up with 40% of all BTC in circulation. By the end of year 13, he's exceeded the total number of BTC by over 25%.
And, since I've got a spreadsheet, if he'd started with 1 BTC, he'd have hit 100% of all BTC sometime in year 15.
So, I have to admit that I was wrong. Due to the fact that no government can produce unlimited BTC (unlike the trillions of dollars and I have no clue how many Euros and British Pounds were extrapolated out of thin air, all to bolster economies during this year's viral insanity), any form of fixed rate return on a limited grow currency will definitely crash against the wall of "you own ALL if it" in a very short time.
But, on the flip side, as long as the rate of return is fake and more new money comes in than goes out, because no real trading is taking place, our investor could stay in and watch his BTC holdings go up into the Trillions of BTC. It just would all be fake.
In the real world, cash limits effect all HYIPS and Ponzis. $10 trillion or so in worldwide Corona virus aid can be arranged by governments, but some "Super Ultra Hedged Triple Back Flip With A Cherry On Top" Artificial Intelligence trading system on forex cannot actually make trillions of dollars. If it was real, as it grew bigger each new trade would shake the world's markets harder and harder. Governments aren't going to print money to make that happen. Many Ponzi schemes and HYIPs I've looked at should have already been trading hundreds of billions if their own creators had started out with even $1 when they claim the system first came online.