Yes, they are. Adeniums are tough plants, similar to most Pachypodiums.
The one major way to lose a mature plant is not to provide proper drainage. I find they do better for me if they are quite pot-bound, meaning there is not too much potting soil around the roots to stay wet during Summer rains as an example. I like to mix quite a lot of Dyno Rok into the potting soil, for good drainage. Clay pots are good to use, not plastic.
I almost lost my large plant by leaving a dense mat of Haworthia cymbiformis on top of the soil, forming a fairly tight cuff around the bottom of the trunk. Things didn't dry up quickly enough and some rot set in. I saved the plant by rooting a bunch of cuttings, which now are again growing well.
