Congrats on the offer. 30% is a lot of money, so o definitely understand. Still, I want to make sure you place things in perspective:
- First, the salary at BCG will increase at >10% CAGR. In 2 years after the next promotion, you will make more money than at your current job
- Second, there is also a significant bonus portion that you dont see in the salary. Dont forget to account for it
- Third, the benefits (healthcare) are second to none. Depending on where the job is, this could be huge. In the US for example, a specialist's visit and an MRI cost $5, and any medication is $4. Good luck beating that. If you have (or plan to have) young kids, the benefit will be substantial
- Fourth, having BCG on your resume will open door throughout your life, and bring instant credibility in the future. View this as an investment as well
- Fifth, you applied and spent a lot of time preparing, so theres obviously something about the job that appeals to you. Not everything is about the money
Having said all of this - you can go back to them and explain your situation. They may try to shift some of your comp forward - or increase it altogether, assuming you do indeed have a very specific and valuable expertise. Theres little harm in going through the exercise.
Hope this helps; congrats again!
PS: for everyone reading who hasn't gone through the interview process yet, please dont structure your final conclusion like I just did! In a conclusion, you will already have done the analysis, so you want to start with the answer first :)