I actually have the same thing. I have a job and I've been working on this startup for some months now. My team and I do understand that we will be making a lot of sacrifice, but the market is ready for us. Whenever we are ready, the market is available. That said, we see our startup becoming very pacey. We are already working on a building project for temporary use. We are looking for funds for our upkeep for up to a year, so we don't struggle too much with basic needs. With all this exciting ideas and opportunities exposing itself, this offer from one of the world's biggest firm just arrived for one of us. Now there's dilemma as we are thinking hard on it. We do know what the future of this company will be. It's very exciting and will grow quickly considering things go as planned. Should this be accepted or rejected. I deeply feel that even if the job is accepted, the satisfaction on building something you've so worked on and believe in is one thing that the job won't be able to provide. While we wait, some other company might be taking over the market. It is a very costly choice, but we didn't expect this to be our first challenge. We do know we will be facing challenges, but this is just too big for a start.
But this is my input to your question. What are you building? Is the vision pulling you or are you trying to run with it? It is a clear vision? Is it something you see developing into a massive firm over time? Do you intend to sell it over time, or keep developing it? Do you have anyone who you've sold this vision to and who is ready to run with you? These are the questions you'll want to ask yourself. One thing you must understand is that it won't be all smooth and you may even feel like giving up. But then, if you so believe in it, pursue it. It may take some time, but it'll surely come out well. What is the assurance that it will come out well? There is no assurance to that, depending on what you're developing and how you run with it. There will be many determining factors excluding the fact that you'll constantly be making sacrifices along the way. This is not a yes or no answer, but I can advice you on one thing. Pray and Plan. Plan a lot and look at possibilities where things aren't working out as they should, then plan for those things as well. Everything may not go as planned all the time, but do plan intensely. Save a lot, and look at the possible expenses. Look at ways you can still make income or receive funding in case things get a little more difficult.
You may be an intense workaholic, but let's be realistic, will you have the time to contribute so much to your project while working? One big thing also is this: the job you're taking, is it an experience that will directly impact the growth of your startup? I mean, the knowledge you'll take out of it, is it something you think you can use towards your startup? If yes, then it may not be such a bad idea. But from my understanding, to a large extent, you have the basic knowledge you need. All you need is to get someone else who can buy into your idea. Someone close enough to work and sacrifice for it. Sacrifice is the most valuable currency of any startup. No matter what you do, your sacrifice will determine a lot of things. So, think deep. I hope you do have the time to think things over while the job offer still pends. I also have a great feeling another offer is coming for me. These are testing my faith in what I have in mind as a startup. But I do know one thing, if I leave those jobs to pursue my startup, that means I'm putting everything into it. Every single thing I've got. But first, even your vision have to be that strong. That being said, it depends on your vision and how much it pulls you. If it pulls you strong enough, then follow it. If it doesn't, and is more or less like a side project to you, then take the offer and give out some of your time to this startup while still working. Maybe little by little you can still build it, and if you're buoyant enough and still think it's worth it, then you can pursue it again.
Hope this helps.