The case for buying and holding stocks is weaker than you might think:
Over the last 50 years, the real returns from equities have been lower than those from bonds in Germany, Japan and Italy. In the Italian case, the gap is almost three percentage points, and that is despite the recent bond sell-off (actually, as Deutsche points out, a 5-6% yield on Italian debt is quite low by historical standards.)
The buy and hold mantra was developed in the US where real equity returns have generally been positive over long periods. But the US was history's winner in the 20th century; enjoying 100 years of political stability while its European rivals destroyed themselves in two world wars and Russia followed the dead end path of communism. The US equity market, in other words, displays distinct survivorship bias. In turn, that bias leads to greater confidence and thus higher valuations; eventually the valuations become so high (as in 2000) that they doom future returns to be disappointing.