There is still a lot between 100k revenue and not profitable at all. What about something like barely selfsustaining (but by that proven to be somewhat profitable) with 2 employees? Or making 10k with a 2-man startup?
If you make about 100k revenue (or if you have otherwise significant traction), you can not only approach investors in Berlin but also ouside, which kind of solves the "Social Proof" problem.
If you are barely selfsustaining, then please stay bootstrapped and grow your business. Otherwise the process of fundraising in Berlin will most likely kill your business.
EDIT: added one paragraph
Social Proof could mean: - You are a Serial Entrepreneur - A famous Business Angel invested in your company - You graduated from a University with a great Alumni Network - etc.
Basically if a potential investor evaluates your Market, Traction or Business Model, then you already lost. If a potential investor invests, because he thinks other investors want to invest, then this is Social Proof.
For example you are talking one hour with a potential investor:
If you talk 90 % of the time about who else is investing and about how to structure the investment round, then you have Social Proof. If you instead talk 90 % of the time about how big the market is, what your revenue model will be any why your churn rate only decreased 2 % in the last month, then you don't have Social Proof.
Also if the potential investors talks about making the investment bigger to increase your run rate and increase your leverage for a Series B, you have Social Proof. If instead the potential investors is asking you if you can decrease your burn rate or recommends you to raise a smaller amount, then you don't have Social Proof.
EDIT: Added one paragraph
But to get those success you need social proof.
It's a hard problem.