With 100k extra € in my pocket I'd spread 20k to 3 different trading accounts (which I already have) but would trade with the exact same strategy on all 3 ones (maybe only with 1 or 2 currency pairs), and then would just live from the 40k left, for a starter. Should be fine to do it like that, you won't need a main job anymore. But this goes only for good traders who can make let's say a monthly consistent profit of 5-10% on all the trading accounts they use. A 5-10% profit from a 20k account can be an income of 1-2k/month (e.g. in Germany the minimal cost of living is around 1-2k€/month, depending on where you live).
With EAs it can be more difficult though because different brokers/trading accounts can be totally different at the end.