[shkkmo]

I'm not sure that continuous growth can be reliably predicted over a 30 year span. There is reason to believe that we may need to move away from economic systems dependent on continuous growth. (edit: though I highly suspect this is more than 30 years away.)

Buying a range of stocks and holding them for the long term may reduce your risks, but that doesn't mean it isn't speculation.

Speculation just means that you are buying something with the expectation that you will sell it for a higher value. When your assets don't produce direct value (such as dividends, rental income, functional utility, etc) then investment in those assets is speculation, regardless of the risk level or time frame.