Yes, definitely not small claims court, especially if given total amount invested.
A correction. ANYTHING can be settled in small claims court you just accept the max judgement of small claims court as the limitation of the settlement. Given depreciation and the lack of business skills one would imagine that net asset value of the company at liquidation would be far smaller than $15K.
Lastly if an investor filed suit as an indivudal (not representing other individuals) for breech of contract only the value of his "shares" (portion of contract) would be relevant.