Ideally, should one craft his/her own investment portfolio, and select asset class and investment on their own?

1. Understand your risk taking profile

2. Choose a strategy which matches 1

3. Look out for fees that will eat into returns

4. Relook steps 1-3 every 5 years

I dislike the term predefined because a large portion of mutual funds are by that definition, "pre-defined".

Crafting your true investment portfolio takes years of experience. Often because most people either over or under estimate their risk taking profile. Most tend to get it wrong the first time.

An advisor will limit your risks based on your cashflow and assets, which will help to keep you staying invested by limiting any dire losses should an event like Covid occur.

It only depends on 2 things. Advice and access.

If you don't need the advice and you have access, you can invest DIY. It'll save you on advisory fees.

If you need advice or don't have access, then you should hire an advisor be it a digital advisor or a human advisor to help you set up the portfolio for you.

Both advice and access costs fees. Fees aren't bad, you just need to know what you're paying for and agree to it.