£3k to invest in an ISA? I’d buy crashing UK shares today to get rich and retire early Peter Stephens | Thursday, 6th August, 2020 See all posts by Peter Stephens “This Stock Could Be Like Buying Amazon in 1997” I would like to receive emails from you about product information and offers from The Fool and its business partners. Each of these emails will provide a link to unsubscribe from future emails. More information about how The Fool collects, stores, and handles personal data is available in its Privacy Statement. Image source: Getty Images. Crashing UK shares could continue to be a feature of the investing landscape over the coming months. Risks, such as Brexit and coronavirus, have not receded over recent weeks, and could continue to hold back investor sentiment in the short run.However, those risks could create buying opportunities for long-term investors. As such, now may be the right time to invest £3k, or any other amount, in undervalued stocks in a Stocks and Shares ISA. Over the long run, it could help you to retire early.5G is here – and shares of this ‘sleeping giant’ could be a great way for you to potentially profit!According to one leading industry firm, the 5G boom could create a global industry worth US$12.3 TRILLION out of thin air…And if you click here we’ll show you something that could be key to unlocking 5G’s full potential…A long-term outlookWhile risks are present for almost all UK shares in the short run, this shouldn’t be a major concern for long-term investors. The track record of the stock market shows that periods of high volatility are relatively common.However, it’s always returned to a bull market following its bear markets, and posted new record highs when doing so. As such, the presence of risks and the potential for a market crash should not dissuade long-term investors from buying stocks.In fact, those risks mean that many stocks now offer better value for money than they did at the start of the year. Certainly, they could yet fall further in price should there be a second market crash. But over the coming years the valuations of many FTSE 100 and FTSE 250 shares suggest they offer strong recovery potential.Furthermore, the short-term performance of UK shares shouldn’t matter to long-term investors. For example, if you plan to retire in 20 years’ time, the performance of your ISA over the next few years is somewhat irrelevant. As long as the stocks held within your portfolio survive a period of economic difficulty, and go on to deliver high returns in the long run, then you’re likely to achieve the desired result of building a nest egg to provide a passive income in older age.Starting to buy UK shares todayClearly, buying crashing UK shares today is a tough task for any investor. Risks may dissuade even the most experienced investors from buying undervalued stocks due to the potential for paper losses in the short run. They may feel that it’s a better idea to hold cash or bonds, and await a period of stronger operating conditions for companies across a variety of sectors.However, history shows the best times to buy FTSE 100 and FTSE 250 shares have been after a market crash. Through focusing your capital on those companies with solid balance sheets likely to survive the short run, and benefit from an economic recovery in the long run, you can build a surprisingly large portfolio.Over time, it could help you to enjoy a greater level of financial freedom in older age. And to potentially retire earlier than previously planned. Our 6 ‘Best Buys Now’ Shares Enter Your Email Address Simply click below to discover how you can take advantage of this. I’m sure you’ll agree that’s quite the statement from Motley Fool Co-Founder Tom Gardner.But since our US analyst team first recommended shares in this unique tech stock back in 2016, the value has soared.What’s more, we firmly believe there’s still plenty of upside in its future. In fact, even throughout the current coronavirus crisis, its performance has been beating Wall St expectations.And right now, we’re giving you a chance to discover exactly what has got our analysts all fired up about this niche industry phenomenon, in our FREE special report, A Top US Share From The Motley Fool. Click here to claim your copy now — and we’ll tell you the name of this Top US Share… free of charge! Renowned stock-picker Mark Rogers and his analyst team at The Motley Fool UK have named 6 shares that they believe UK investors should consider buying NOW.So if you’re looking for more stock ideas to try and best position your portfolio today, then it might be a good day for you. Because we’re offering a full 33% off your first year of membership to our flagship share-tipping service, backed by our ‘no quibbles’ 30-day subscription fee refund guarantee.