What are your goals with MTB? If you’re just gonna have fun on it, sure build whatever you want if you have the time, knowledge and money. I wouldn’t make it your “dream” build though, because your wants and needs are likely to change as you get out on the trail and start racking up miles, experience and races.
My journey was in the beginning of April 2017 when I bought my first MTB hardtail (first bike actually) to go out with friends. After one trail ride I fell in love with the sport. I wanted to immediately ride several times a week and I couldn’t get enough. None of my friends wanted to ride as much as me so in May 2017 I entered my first XC bike race to see if I liked it. LOVED IT!
Did another race then decided I wanted to be seriously competitive. Sold my entry level hardtail and bought a carbon hardtail race machine. Finished off the 2017 race season and was fully invested in cycling. Over the winter I bought an indoor trainer. By March 2018 I had sold my carbon hardtail and picked up a full suspension Scott Spark RC 900 World Cup. Raced that bike all 2018 season and had upgraded to carbon wheels and a few other tweaks. Also picked up a fatbike for winter 
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So my passion for MTB developed and progressed resulting in 3 bikes in 1 year. I was also able to keep from getting divorced in the process… but just barely though 
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