IMO and all speculation and not adviceHere is an alternate thought process.
Imagine the following...
You do your research and found an investment that you put in $100,000 in the last 12 months. Lets say you average is 5c per share being 2,000,000 shares
(some here are much lower than that!)
(...and some may wish they had invested more 
)
This company has excellent prospects for getting to production and plans for dividends ...and those initial dividends start at 1c per share in 2024 and grow over time.
The simple math of this scenario is that in 5 years of placing your investment you are receiving a 20%pa return on your money for the Life of Mine or $20,000pa. However, the opportunities are growing for your company and dividends increase over time. If dividends grow to 5 cents per share you are receiving returns of 100% on your original investment being $100,000pa! All the while the growth in SP remains in place for you to sell and take profits anytime you like!
Where can you get a 20% return and have you capital grow at the same time?
...and should the upside occur IMO $100,000pa of income in retirement would put you in the top 5% of Australians! ...and you can put it in trust for your descendants! 
Now enough speculation, lets get back to reality...
IMO There are plenty of investors here on HC with multiple millions of Shares and Options with a average cost per share sub 5c after option conversion. I recall reading someone recently bought 3,000,000 heads in the 5c range. Some of us here after conversion will have multiple millions at an average at or below 2.5 cents per share. You can do the math...
IMO I think most here would agree it is possible ADN could pay dividends of 1 cent per share in the near future (before 2024). Therefore IMO, and based on the PFS, it is possible that anyone buying heads with an average of 10 cents per share could achieve a 10% return on their initial investment for life of mine. (and yes, and the SP is yet to hit 10c). All while your investment grew in value as well.
As to risk! IMO If ADN goes to production the risk has been mitigated as the markets they sell to have been established for centuries. ...and investors can mitigate their own risks but diversifying into other investments making ADN only a percentage of their portfolio.
As everyone will have a different set of needs and tax position, here are some key considerations and questions...
Sell?- How much will you realise?
- What capital gains tax will you pay?
- In today's market what return can you achieve on your post CGT funds?
- When do you sell? e.g. whilst working and paying tax or post retirement?
Keep?- How much is your investment now worth?
- How much CGT will you pay? $0
- What is your percentage dividend return on your initial investment?
- What is your percentage dividend return on your current capital value?
- How does your return compare to what's available on market?
I can't speak for others, but I can share that in my case keeping the investment far out weighs any sell. Therefore I am prepared to wait for dividends...
... and if forced out by a TO well IMO we all made good money.
ALL IMO and for sharing and education not advice
Please seek your own professional advice
GLTAH
(20min delay)