No publisher has an unlimited budget, and that is also true of self-publishers. Determining the format of your publication affects the overall cost of publishing, so it’s important to minimize your risk.
Ebooks and print books have different costs associated with them. While ebooks are cheaper to distribute because there are no physical shipments, professional-looking ebooks require additional investments that print books might not: in special formatting, adding multi-media (and clearing the rights for them), proofreading specifically for the digital product.
Print books may not involve these types of investments, but you’re certainly paying plant costs (for paper, printing, and binding). And both also require the same investments in clearing rights for photos and/or music lyrics, layout and design, the editorial process, marketing and publicity. So both formats have their own costs, and they share costs as well.
It’s also important to understand the purpose of your publication. If you’ve written a novel or a memoir, you may want to test the market by publishing it first as a Kindle file, with a limited print run or print-on-demand option for family and friends. If you’ve written a book demonstrating your professional expertise, you may want to publish it primarily in print to begin with (to give away at conferences and trade shows, to attract business leads), and put it out as an ebook later on, if you find you’re experiencing demand for that format.
Self-publishing has the benefit of being agile – you can experiment in small ways, with iterative approaches, to find what works for you. This minimizes your investment, and helps you fully understand the costs involved in multi-format publishing before you commit to them.