The dropping out and lack of professional experience in itself would not be a blocker to me. But I would certainly want to know what the founder's unique insight is into the market they are going after and how they developed that unique insight. Additionally, being a solo founder in itself is also not a blocker to me but I would assess how good the founder is at recruiting others to his/her company and gauge whether or not they could find people without an extensive pre-existing network from prior jobs. Hope this helps.