The counter to that, however, is the meterials risked in the process.
You can go fight a raid with a group, lose, and at worst, spend a round at the repair shop and lose a bit of gil.
You can loose several millions just trying for one good tripple meld, solo or not.
So it balances out. Tripple meld gear has lower entry requirements, but higher long term cost/risk.
Where Raiding has higher entry requirements, but low long term risks.
That should justify the rewards being equivalent.