The only place where you can find users like that which can even give cash for the bitcoins is localbitcoins.com I never tried that cash option but i can see there are many buyers who can give cash to buy bitcoins in my locality and i think you can find some your locality as well.
i think it will safe to withdraw our bitcoin with localbitcoins because i see in localbitcoins itself, many recommended seller that will help us to withdraw our bitcoin and we can get our money in many currency/fiat, so don't worry if you want to exchange Bitcoins in EURO.
but for 10.000 EUR within a day, i think its really hard because not all recommended seller have that much amount to make a deal with buyer, so better you make a deal with two or three seller.