The DIY-or-hire decision for WordPress work comes down to three questions. Here they are, plus the specific threshold for each one.
Question 1: How big is the budget?
Under $1,000 for a full site build: you are doing it yourself. The minimum professional rate for a custom WordPress build is around $1,500. Anything under that, and you are either getting a template-with-your-name or you are doing it yourself.
Between $1,000 and $3,000: this is the do-it-yourself-with-help zone. You do the content and the basic setup. You hire someone for the technical bits (theme configuration, plugin selection, performance tuning). Three to six hours of pro help at $100-$150/hour.
Over $3,000: hire it out. You are past the point where your time spent learning WordPress beats your time spent on billable work.
Question 2: How technical are you?
If you have never touched WordPress, you will spend 30-50 hours learning the basics before you ship a real site. That is worth $1,500+ in opportunity cost. Hire it.
If you have shipped a couple of sites but never done anything custom, you can probably handle a 5-page site with a clean theme. Anything more complex, hire the technical parts.
If you have shipped multiple custom sites and you know your way around PHP and CSS, you can do most of it yourself. The question becomes time, not skill.
Question 3: What is the cost of getting it wrong?
A wedding photographer portfolio site that looks bad does not cost much. They will redo it in a year anyway.
A small-business lead generation site that is broken costs real money. Every day the contact form does not work, you lose leads. That is $200-$2,000 per day in opportunity cost, depending on the business.
An e-commerce site that loses an order because of a checkout bug costs real money per every bug.
When the cost of getting it wrong is high, hire it. When it is low, do it yourself.
The matrix
Budget under $1k + low technical skill = DIY or skip
If you cannot afford a pro and you cannot do it yourself, save up. A bad site is worse than no site.
Budget $1k-$3k + medium skill = DIY with a few hours of pro help
Do the content. Hire the architecture. Save the rest for maintenance.
Budget $3k+ + low skill = hire it fully
Skip the learning curve. Spend the budget on a real site. Maintain it yourself afterward.
Budget $3k+ + high skill = DIY but use a pro for review
Build it yourself. Hire someone for 2-3 hours of audit. Catch the things you missed.
The honest answer
Most small-business owners should not be building their own sites. They should be running their business. The site is a tool. Hire someone to build the tool. Spend your time on the work that actually needs you.