I used to think this way too, but now I wonder. Illegal insider trading is pretty well defined and requires an insider knowingly share information with someone who trades using it. If my wife is friends with the wife of a corp dev guy for a local company and I hear through her about him being out of town on a trip to a town I happen to know houses an attractive acquisition target for their company, it doesn't take much to put two and two together and it would be completely legal to trade on that. My trades alone might arouse interest if it's thinly traded, and a bunch of others pile on just because they see the smoke and hope there's fire. Next thing you know ex post facto it seems like a clear case of insider trading but actually wasn't. I read the SEC enforcement action on insider trading and it seems incredibly sophisticated and very hard to evade their screens. Some of the guys who get caught have gone to great lengths to cover their tracks and aren't even greedy about it but still get caught. I just don't see there being rampant insider trading going on that they ignore based on the cases I read. Could be a manpower issue though I suppose.
We don't have to fear the insiders. We don't have to investigate where & who are the insiders. Insiders are no different from us outsiders as both of us want to profit from the market. We just need to know how to trade. Just focus on the chart and that's sufficient for us to earn $$$.