That's being delusional. This is because a ton of websites get launched every single day and there are only a handful of them that make it to the best positions in the search engine.
After you have launched your website, the next steps should be to actively put in efforts to gain maximum visibility on the search engines (like Google, for instance). You can imagine the amount of visitors you'll have on your website if your site ranks on the top spots in Google. That will surely make your site pretty darn famous and get your cash registers ringing. After all, that is what every business owner dreams of!
There are two important branches of doing good SEO - on-page SEO and off-page SEO:
We'll start with the first one
a) On-page SEO: This is about optimizing your website's content to align with what Google wants. When you are publishing a page on (say) best car dealership in Singapore, and want to come up in the search results whenever someone types that in Google. You need to use this phrase as an H1 tag on the page and throw in a couple of H2 and H3 heading tags too (if you think is appropriate).
You need to optimize your images you use on your website with the correct titles and alt-tags too. This is to give the search engines better understanding what those images are.
You should also be writing amazing content that is unique and provides value to your users. This is very important as search engines are looking for informative content to provide to their users as well and if you happen to have good content, then your site will be given preference over others.
b) Off-page SEO: These are techniques you need to do outside of your website (that is why it is called off-page). The most common forms are:
Building backlinks: These are links you need to place on other websites pointing to your own. This ensures that your site is seen as 'trusted' by Google and other search engines crawlers and will start pushing the needle in the right direction.
Guest posting: You should be investing a lot of time writing guest posts. These are posts that other websites place on their websites for their readers. If you are good at something, then you can write detailed guest posts and offer them to such websites who will in turn gladly accept it if it meets their criteria.
Forum links: These are links from other industry forums that are in your niche. If you find them, be sure to make a good profile and place your homepage link therein. Some interested visitors will be curious to check your profile and may become your customer after checking your site's link.
These are some of the most common methods of getting started with SEO 101. If you are going to take one piece of advice from this, then it should be to start implementing small techniques right away and do it consistently. You will notice that over a period of time, your website will begin to gain authority and will hopefully conquer your competitor after some time.