Frankly, that's just a bad case of 'An idiot and their money are soon parted'. An annual return of 16% means a coin would have to appreciate by at least 40% on typical hammer prices in the first year just to cover costs. 20% commission to buy at auction, the investment company's annual charge - say 4%, plus the 16% promised return. They might have assumed that they would purchase privately at typical hammer prices, but the material simply isn't available to buy. A fundamental part of investments is liquidity, which has never been a feature of coins. When something can be off the market for a hundred years, who is going to invest in it? When a coin changes hands too frequently it usually raises the question as to what is wrong with it.
Although coins are clearly an asset, liquidity issues mean they can only ever be peripheral investments.
In September the BBC is going to have 'investment coins' as the target for one of its 'Rip-off Britain' programmes. GeoffT is on it giving a collector's viewpoint. I was asked to give a dealer's view, but declined on the grounds that the programme title did not offer the possibility of a balanced argument. Whilst I felt that there were undoubtedly companies pushing material of questionable investment quality, the most important issue was that of caveat emptor, which in today's nanny state mentality is increasingly legislated to irrelevance. It never ceases to amaze me that people will spend thousands on something they know nothing about, yet would insist on taking a potential new car for a drive, or would ensure that the new carpet or curtains matched the existing decor.
People need to be held more accountable for their own actions rather than going down the no-win, no-fee route, which absolves the consumer of any responsibility.