Are you hesitant to travel in Bangkok because of spicy Thai food? Don't worry. There are other restaurants and fast foods here which are 100% not spicy.
Those local food here are cheap but, you can also ask them to make it less spicy if you wanna try something different. In Thai, "phet nit noi" means a little spicy and "mei phet" means not spicy.
But, if you really don't wanna take chances of getting this kind of food... you don't have to worry about it.
There are 24/7 convenient store nation-wide such as:
7-11 Convenient Store
Foodland (Convenient store and fast food)
Tesco Lotus Express
Here are only some of the Restaurants and Fast Foods here:
Not to mention that you can save more money if you cook food and there are food/goods that are microwaveable. Like ready to eat pizza, spaghetti, and many more at the supermarket and groceries like Tesco Lotus, Big C, Carrefour and Foodland.