'if the SP were to go to say $3, I am pretty certain I would be...

'if the SP were to go to say $3, I am pretty certain I would be tempted to take some serious profits'

This is the dilemma that I, as well as many others, might need to deal with.

When I first brought IMU, they were about 6% the value of my holdings.

If they became worthless, I was prepared for that - been there before with other shares falling to 15 to 25% of my buy price.

IMU are now over 60% of my holdings (which includes the shares which have fallen 80% and I am still holding).

As you said, everyones situation will be different. Some people need the money to buy other things, some people invested in the hope of future income/capital gain to fund retirement etc

Do we take some money off the table and at which point?

Or do we hold for 5, 10 or 20 years and watch the share price increase by another factor of 5, 10, 100 or more and hopefully receive dividends as well?

Sometimes my crystal ball works better than other times...

Good Luck.