are people taking into account inflation?
e.g. dg says £60k a year, but you would need to have enough capitla that after 40% capital gains you would have that amount left (so need £100 k in interest each year, so need to invest 2m if assuming 5% return)
ANd in 30 years time, £60k won't buy you as much as it does now - college fees, clothes, food, holidyas etc will all have gone up. so if you intend to re-invest an additional 10% of your capital each year, after you pay tax, and still have a decent income (say £60 k index linked).
You nedd about 3 to 4 million.
Which just covers 2 or 3 kids going to college, doesn't buy them each a 3 bed semi to get started in life!