I feel guilty if i want to buy myself something expensive. How do i change that?

It's great that you're deliberating over a huge expense!

It's worth considering - What your financial goals are and that the expense doesn't result in you deviating from your goals.

You shouldn't have to feel guilty IF:

• you have healthy financial habits
• the expense is well within your means and budget

Another check is to ask yourself : if you would still be purchasing this item if you weren't allowed to tell anyone about it. Sometimes we do things for the sake of leaving an impression on others. What you really don't want is to spend the money, only to realize that you never really had the inner desire for it in the first place.

Just split the cost over a defined period of time, like 1 year or so. That will become more "affordable" in a split second (much lesser than 35 seconds).

What I usually do is setting aside some money for self-indulgence every month

If i have to spend more than I plan , I will try to cut down some expenses and shift it to the expensive item I want. Eg less bubble teas or coffees from kopitiam instead of cafe.

It's ok to reward yourself, you deserve it :)

Seems like monetarily, you can afford. Then it calls for mindset shift.
Does the sum of money make you happy, or happier when it convert into the product for you to own?
You mentioned "expensive item", so I'm assuming it is something physical. But the same can apply to an experience too, eg staycation or cruise-to-nowhere in this dreadful no-travel period.