Rupert Hargreaves explains why he's avoiding buy-to-let when it comes to retirement saving. : For a whole generation of investors, buy-to-let investing has been the perfect way to boost pension income. A Goldilocks scenario of rising rents, rising property prices and falling interest rates, has helped buy-to-let investors profit substantially over the past few decades. A light touch approach to regulation and taxation has also helped buy-to-let investors achieve substantial rewards. But it now looks as if the winds are changing for buy-to-let investors.