2021 was a banner year for cryptocurrency, with digital tokens, such as bitcoin and dogecoin, hitting all-time highs and making millionaires of investors. The overall crypto market briefly surpassed $3 trillion in value and the growing popularity of digital assets like nonfungible tokens, or NFTs, helped bring the once-niche technology to the mainstream.

While tokens like bitcoin and dogecoin have different levels of technological development and scarcity, both saw strong growth in 2021, along with other top coins. Read on to see what a $1,000 investment in four popular cryptocurrencies at the start of the year would be worth now. (All prices are as of 3:30 p.m. on December 28.)

But take it with a grain of salt: When it comes to crypto, remember that past performance is no guarantee of future returns, and experts caution investors to put no more money into cryptocurrencies than they are comfortable losing.

If you do decide to get into crypto, consider not making a large purchase all at once, but instead dollar-cost averaging by spreading it out into smaller purchases over time.

Bitcoin

• Price on Jan. 1: $29,290
• Price on Dec. 28: $47,795.40

A $1,000 investment in bitcoin at the beginning of the year at a price of $29,290 would have bought you 0.034 tokens, which would be worth about $1,632 at Tuesday afternoon's price of $49,150 per coin.

The world's largest cryptocurrency by market cap had a strong 2021, with its value increasing about 65% between Jan. 1 and late December. In February, it hit a $1 trillion market cap for the first time, but has since pulled back to close to $900 billion.

Ether

• Price on Jan. 1: $730.30
• Price on Dec. 28: $3,816.67

The value of a single ether, the the Ethereum blockchain's token, is up more than 400% over the past 12 months. A $1,000 ether purchase on Jan. 1 at a price of $730.30 would now be worth about $5,226.16 at Tuesday afternoon's price of $3,816.67.

Supporters of Ethereum say the blockchain will become more scalable, secure and sustainable after its Eth2 upgrade, slated for 2022, during which the network will shift to a proof of stake, or PoS, model. Currently, Ethereum operates on a proof of work model, where miners must compete to solve complex puzzles in order to validate transactions. This model is frequently criticized for its environmental impact since it requires an extreme amount of computer power.

The shift to PoS will allow users to validate transactions according to how many coins they hold, rather than the energy-intensive mining rigs used now.

Solana

• Price on Jan. 1: $1.53
• Price on Dec. 28: $181.18

If you had invested $1,000 in the Solana blockchain's native cryptocurrency SOL at the beginning of 2021, when one coin cost $1.53, your investment would have grown to about $118,418 at Tuesday's price of $181.18.

Despite only launching in 2020, Solana grew by more than 13,800% over the past year and is currently the No. 5 biggest cryptocurrency with a market cap over $57 billion. Solana is seen as a competitor to the Ethereum blockchain. Its founder, Anatoly Yakovenko, designed Solana to support smart contracts, which are collections of code that carry out a set of instructions on the blockchain, and the creation of decentralized applications, or dapps.

Dogecoin

• Price on Jan. 1: $0.0056
• Price on Dec. 28: $0.18

If you put $1,000 into dogecoin at the start of the year at a price of $0.0056 per coin, it would now be worth $32,142 at Tuesday's price of 18 cents. Not bad for a digital token that started out as a meme-inspired joke.

The cryptocurrency, whose popularity was fueled in part by Elon Musk, grew by as much as as much as 12,000% in the first half of 2021. However, dogecoin's value fell in the latter half of the year.

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