It's important to reiterate a key point that's been both stated and implied above -- do *not* look at this as a money-making opportunity. If you profit from the project, great, but take it on with other goals in mind.
As much as the credibility factor, a professionally published book opens all kinds of doors. My first trade publishing deal was horrible on paper, because I had no idea what I was doing. I got 32 cents royalty per sale (book published in 1990), and it was work-for-hire (i.e., I didn't own the copyright). I lost money on the project and couldn't create any ancillary products from it for additional income streams due to it being work-for-hire.
However... that book was done for Warner Bros. and was a collaboration with the rock band Iron Maiden, ultimately leading to sales in more than 20 countries over the course of the decade. It was trial by fire that made me much smarter for later book projects and deals. And most significantly, the name value of Warner Bros. and Iron Maiden has carried residual "weight" to this day, more than 25 years later -- a valuable piece of my publishing history that's been the difference in getting other book deals, projects, clients, and speaking engagements. (Of course, I also got to spend time with the band, meet other rock stars, and have backstage access at huge concerts! Priceless.)
So, in considering your book project, be sure to take a 30,000-foot view as to whether this could lead to bigger and better things, and see the book as a tactic within an overall strategy. Then measure down to your anticipated investment (literal expenses, time spent, opportunity cost) and determine whether the project makes sense. Again, unless you have a significant platform with loyal followers and/or an existing speaking schedule to leverage, you're best off assessing this project based on little or no expected income from book sales and royalties; whatever does come in can be bonus money.