Compound growth - looking for some advice

[GOAT]

Hi Folks

I want to retire early and stop working in about 20 years and figured that my best way of getting there is through investing in ETF / PIE funds and letting the compound/exponential growth do the work.

I'm thinking of investing 250k initially, and then 50k per year for 20 years, and I estimate the growth to be somewhere between 10% and 15% average across the 20 years, which would mean I would end up with a figure between 4.8m to 10.7m at which point I should be able to comfortably retire.

My investment would be weighted evenly across 5 different ETFs / PIEs as I don't want to be exposed to a single market or fund manager etc. I haven't made a decision on which ETFs / PIEs, but I was considering the following:

1. Piefunds - Australasian Dividend Growth
2. Smartshares - US Large Growth (USG)
3. Kernel wealth - S&P Global 100
4. Kernel wealth - S&P NZX20
5. yet to be determined

I'm making the following assumptions:

1. Growth funds work in the same way as compound interest e.g. if one was to invest 50k in a growth ETF and get 10% growth year on year then it will grow in first few years to 55k, 60.5k, 67k etc. as it will grow based on both the principal and also exponentially with the increase in value of the fund.
2. If my above assumption is correct, then we would see the same application for dividends being reinvested.
3. There are ETFs / Funds that could return between 10% and 15% growth per annum across 20 years (this would be averaged as I'm taking into account there will be some years in the negative and some years above 15%)

Questions:

1. Is my assumption #1 correct?
   
   • Would 50k at 10% growth per year increase by 55k, 60.5k, 67k, or;
   • Am I wrong and that it is only principal amount would grow e.g. 55k, 60k, 65k?
   
   
2. Is 10% to 15% growth per annum feasible? (taking into account the management fees etc.)
3. Is investing in these ETFs / PIEs via a provider like smartshares or piefunds etc. secure/safe? i.e. will the investment be in my name in the off chance the provider folds?
4. Any thoughts/feedback on my selection of funds?

Just looking for some advice to avoid any newbie mistakes, so any tips/help would be much appreciated.