I regularly read claims from people of 50%+ returns in months let alone years.
It worries me, not because it isn't true (though in many cases it isn't) but because it sets an unrealistic anchoring point in people's minds. (An anchoring point is when a set of information becomes the starting point from which you reference). Personally I am trying for a 10%pa return, though I recognise that this is well ahead of the norm for what will be achieved in the current low inflation, low return environment.
It worries me, not because it isn't true (though in many cases it isn't) but because it, for some will activate Recency bias the effect where people attribute overimportance to the last piece of information received.
It worries me, not because it isn't true (though in many cases it isn't) but because so many people claim these huge returns that people will be duped into thinking these returns are likely. Whether its Survivorship bias or Attribution or Group Think these claims of huge returns drown out the virtually non existent claims of low returns.
It worries me, not because it isn't true (though in many cases it isn't) but because it doesn't put the return into a risk or historic context. If I go to the Casino and bet on black I can get a 100% return or 0%. When these people claim these 50% returns I think they ought to be within a timeline that honestly lets you assess the risk that they took on to make the return (all on black) and what they have been doing before and after the return. Not just the bet on black that went well, but also all the times it came up red.
It worries me, not because it isn't true (though in many cases it isn't) but because it often fails to put genuine monetary amounts into the equation. If you have £10 and make a 50% return you get an additional £5. Not much more than a cup of coffee. If you have £1,000,000 and you earn 2% you get £20,000. A much more useful sum. As a matter of maths if you have £10 and can compound at 50% and your neighbour has £1,000,000 and can compound at 10%. It will take you over 30 years to catch up. As it is nobody has ever been known to do 50% for 30 years so the chances are the neighbour will be richer even after 40 years.
It worries me, not because it isn't true (though in many cases it isn't) but because in most cases the people claiming the huge returns have something to sell you. Most financial services firms do not make money from the strength of their financial performance, but from the Assets Under Management (AUM) on which they charge a fee. Their marketing skills are at least as, if not more, important than their financial skills.
Ultimately it worries me because it creates another barrier to people setting out their financial aims in a sensible manner and developing an investment strategy that they can enjoy and that allows them to sleep at night.