I can see it now, your massive 18ft tall boat, rolling to 40 degrees from side to side, with an interval of 4 seconds. You can't go out to the main deck, so you stay inside the superstructure, but that doesn't really help, as you can barely walk around between decks there and when you do, you are most likely to be hit by sliding furniture, or fall and slide for some 15-20 meters before seriously hurting yourself and THEN have a table dropped on you. Can imagine you thinking "if this time it won't go back into upright position, if it flips, you'll be stranded in 10-12 meter waves 500-800 nm (maybe more) away from any sort of dry land". Also I can imagine you in your cabin trying to get some sleep before having to wake up in the morning, in hopes that you won't be thrown off your bunk in the middle of the night, and have your back broken against something.
Wait... no... I don't think you experienced that in your inflatable dinghy on a lake. So.... yeah... you haven't experienced what it is, and your comparision is plain wrong.