Yes, it's common to calculate profits of bosses without uniques to get an idea of what you'd make as a base.

That aside, the blade is a very rare drop. You can see the amount of Gauntlet completions on the scoreboard, it's up to 65,000 now, and there's still a very limited amount of blades in the game, clearly indicating that the drop rate is AT LEAST 1/1k. Considering it takes 7-8 minutes to clear you're looking at 100+ hours to get it. It will clearly settle lower than rapier so there is no way you're getting above 1m/h from uniques from Gauntlet, which means the gold will naturally never average above 1.5m/h.

Also, it is far too easy to be end game content. Raids is end game content, this isn't. Normal CoX solo is far more difficult than this, and Solo challenge modes are way harder than corrupt gauntlet. This is mid-high content and the loot reflects it.