Miners tend to keep whatever coins they think will increase in value, and sell when they see the coin going sideways or down. Botnet owners have little of no overhead, so they just dump like mad. There is absolutely no positive aspect to having botnets on your coin.
1. I would like to see actual evidence of this as opposed to people just stating it. Is there any?
2. Not having a high cost structure would reduce, not increase the incentive to sell. The people who are most motivated to sell quickly are those with high operating costs (electricity, cloud mining, etc.). So this argument about botnet behavior is illogical in addition to unproven.
#1 Most botnets originate in broke, Eastern Euro areas where money now is more important to them than a speculative instrument in the future.
#2 If you receive something completely for free with no overhead, you personally value it less than if you had to actually work to obtain it.