Lyft. John Zimmer pitched me an idea called Zimride back in the late 2000s it wasnt yet ride sharing, it was for employees and students to carpoool to work school together. If I remember correctly the valuation was $150k at the time. I was a CEO of a tech startup in the sustainability space and working with universities and big corps. John thought there was synergy. So did I, but I was focused on my own startup and passed on the $25k he was looking for to develop the idea.
Around 2014 I was watching CNBC one night and saw John on the TV I turned up the volume to find that my investment would have likely made me a billionaire. My startup failed by the way we raised $3M and the assets sold for 10k in 2014
If you take the money now. You will have a fat tax bill, you'll be left with a nice amount - but not a life changing amount.
Its unlikely you will regret the second option. Even if somehow you fail. The lessons you will learn from stage 2 of growth are worth it and will elevate the way you operate as a person and entrepreneur forever. You also have something you know and seem to know how to scale.
I advised a company 10 years ago in the same place. We decided to stay the course on and grow it - but we made a big investment into the best person we could afford that would run the day to day (we paid $300k for an killer sales guy who could eventually run the business). Today that business does 4X that revenue and is run by the person we recruited - my client takes 2.5X the owner distributions they did back then and does very little work.