Although all the messages appear to predict dire consequences if you don't Esc / PS equivalent, only one is a true prediction of line / rod break: "You have a terrible feeling about this one". Reel your line in when you see this message, ignore the rest.
Feel free to experiment with fighting the fish despite this message, of course. I don't recommend it, even if you have a lot of money.
By the way, don't feel like you have to get the best gear to fish. I have done well, initially, with the lowest level equipment possible, and Mog Enhancement Fishing (Layout one Brass / Earthen / Ceramic Flowerpot in Mog House, has to be in your Mog inventory to be placed, not your Character inventory) If you have other furniture, you may need to buy more flowerpots, or even remove furniture to get the energy level of the other Enhancements to be less than that of the flowerpots. Tie goes to the first Enhancement that had more energy than the others, e.g., if you have '6 points energy' in Enhancement: Water, from 2 Water Jugs, and then Layout 3 Ceramic Flowerpots of 2 energy each, you will continue to have Enhancement: Water, because the energy levels are tied and Water was first. If, however, you remove one Water Jug, the flowerpots' energy, at 6, will be dominant and you will receive Enhancement: Fishing. If you then replace the 2nd Water Jug, the energy levels will again be tied, and remain Enhancement: Fishing.
Why fishing for flowerpots? No reason. It is an expedient game mechanic, and a reward for people who try out gardening.

3 gil each, i'm rank 9 fame, lugworms are 10gil each

Vendor inventory changes based on the nation's conquest rank. Currently on Shiva, Bastok is number one so Gelzerio is selling little worms. Unfortunately I don't know if he sells them at rank 2 or not.