Not so, I would just buy whatever the insiders are buying a bit later. The argument against insider trading is a bit weak because it seems impossible to enforce

Not so, I would just buy whatever the insiders are buying a bit later. The argument against insider trading is a bit weak because it seems impossible to enforce effectively and I don't see why anyone would assume insiders are anything but active in the market. Picking on stocks as an example, there is a background fair market rate that everything should theoretically achieve. Insiders way outperform that - but most people are in the market to target the background rate, not the outlier rate insider traders can achieve.