€50 a day just on food and drink? geeez! lol - I allocate myself around that amount per day as well but that includes everything - food, drink, day trips, gifts etc . I took €700 with me back in August for the 2 weeks and i still didn't spend it all - shame i can't take that skill home with me lol
I generally end up having to make my own breakfast most days because places aren't open at the time i like to have my breakfast. Eggs, bread, cheese & croissants etc don't really amount to much so that probably saves me a good amount of money.
I very rarely have lunch (unless you class ice cream & Mythos as lunch lol) because i'm just not hungry during the day. I find the heat suppresses my appetite so again, i'm not spending much there either. Only a few € on drinks.
My evening meals, most of the time, i'd say i spent around €20-€25 max including a tip. That's usually a starter, main and a drink or two. I don't eat out every evening either. A pizza from Lithero's is only about €10 and i would have the other half the next day.
Most of my money goes on my day trips and buying little mementos from the trip. Oh and stocking up on boxes of white chocolate oreos to bring home lol
If you're trying to find places to save money on, i'd suggest making your own breakfast for at least half of your stay. Also, make your own sandwiches for lunch and then eat out on an evening as you usually would or maybe alternate days instead. I find the supermarket prices are pretty reasonable if you stick to the local/greek brands. I find the popular/well known brands are much more expensive due to them having to be imported.
Instead of having another drink after your meal, buy some from the supermarket and have it on your balcony or on the beach instead. I paid €4 for a bottle of retsina in a restaurant and then saw it in the supermarket for €1.20!!
I don't usually make an effort to cut back on things on holiday because it's a treat and don't want to be fussed on what things cost. Which is easy for me to do as i have no one else to pay for. Plus, i always put my spending money aside as early on as possible so it doesn't look like i'm spending as much when the time comes