I'm pretty sure that's "common wisdom" from the ITER project, not a true statement about all the alternate fusion proposals. Starting up a Bussard reaction does require a certain amount of energy, but not to a "requires a fission reactor" extreme.

(Besides, it might be possible to launch a running Bussard reactor, jumpstarted on the ground. Given how it works, 8 or 10G vs the 1G it already has to work in may not be a significant difference. It almost certainly would be possible to launch a running focus fusion device, though I'm a lot more skeptical about that one. Well, I'm skeptical about the whole field, but some are more plausible than others.)

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