Compound interest is not, in fact, magic - the money has to come from somewhere. The safest investment is government bonds, in which case it literally comes out

Compound interest is not, in fact, magic - the money has to come from somewhere. The safest investment is government bonds, in which case it literally comes out of future tax payments. Alternatively, you can invest in corporate bonds and stocks, in which case - in the current economic climate at least - you're providing economic stimulus that pumps the bubble a little higher and drives down long-term returns for everyone else who's looking to retire in the future.