Nvidia (NASDAQ: NVDA) shares have generated amazing gains for me in recent years. But I’ve made some big mistakes with the growth stock that have cost me a dearly.

Looking ahead, I’m determined not to make these same mistakes with another stock I’m excited about. If I play my cards right, I reckon this stock can deliver blockbuster gains in the long run.

I should have pulled the trigger earlier

I can pinpoint at least three mistakes I’ve made with Nvidia stock over the years. The first was not buying when I originally spotted an investment opportunity. Looking through old WhatsApp messages, I started talking about this stock with pals back in September 2016.

“Sticking Nvidia on my watchlist. Might buy it during a pullback”, I wrote at the time.

Annoyingly, I didn’t buy it until about five years later. And that cost me a fortune. Over those five years, the share price leapt about 15-fold.

If I’d invested just $1,000 back in 2016, it would be worth nearly $80,000 now.

I didn’t buy enough shares

In August 2021 (well before the artificial intelligence (AI) craze), I got really excited about Nvidia and finally bought the stock. However, in hindsight, I didn’t buy enough.

Don’t get me wrong – my position wasn’t tiny. I’ve still made strong gains in monetary terms. But it could have been bigger given my bullish view. Taking a larger position would have led to larger profits.

I took profits too early

Finally, the third mistake I made was taking some profits off the table too early. When the share price rocketed up from around $15 to $50 last year, I sold around 20% of my holding.

That was a dumb move. Given the rate at which the company’s revenues and earnings were rising, I should have held on to these shares.

Lessons learnt

Now, everyone makes mistakes when investing. So I’m not going to be too harsh on myself for these moves. However, I’m determined not to make them with another growth stock I’m excited about – Uber (NYSE: UBER).

This is one of my top stock ideas for the next decade. I’m really excited about the company’s potential on the self-driving taxi front as I believe Uber’s likely to be the platform that a lot of autonomous taxi companies operate from.

It’s worth noting that Uber already has robo-taxis on the road in some US cities in partnership with Google’s Waymo. And a few weeks ago, it announced it’s launching in more cities.

Like Nvidia, this stock’s going to be volatile. News in relation to regulatory intervention or competition in the robo-taxi space could send its share price down.

But I reckon this company has tons of growth ahead of it. Given that it only has a market-cap of $156bn today (versus $809bn for Tesla), I’m really excited about its potential.

The good news is that I got in quite early. I started buying shares at a price of around $40 last year – below the IPO price of $45.

I’ve also built up a decent-sized position. Today, Uber is just outside my top 10 holdings.

Now, I just need to hold on to my shares through both the ups and the downs. This will be the hard bit!