Attempting to replace a dead link with your own is easily and routinely identified as spam by the Wikipedia community, which expects dead links to be replaced to equivalent links at archive.org. Persistent attempts will quickly get your account blocked, and your webiste can be blacklisted (the Wikipedia blacklist is public, and there is evidence that Google uses it to determine rankings), which will have negative SEO consequences.
Understand how a niche website works. A niche website focuses on very targeted, specific information. The content must be specific, useful and interesting to your target audience. Successful niche websites get anywhere from 1,000 to 10,000 visitors per month. You build content on a particular keyword, and you make passive income with Google Adsense or through affiliate links.