I never really understood this mentality. I haven't met anywhere, whether it's a funded startup founder or the CEO of a Fortune 1k company, or a single parent with a full-time job, who doesn't have 20 minutes somewhere they can spend reading.
I can understand if the argument is that it's so far down the list of priorities that by the time you get to it you'd rather just go to sleep. I get that. But don't say you're too busy to do it, say it isn't enough of a priority.